Coordinate Geometry: 2 marks Questions (CBSE Class 10)
57 different 2 marks questions on Coordinate Geometry from CBSE Class 10 Maths board exams 2022–2026, newest first.
A (– 2, 3) and B (4, 1) are end points of the diameter of a semi-circle. The semi-circle intersects y-axis at point P. Find the co-ordinates of the point P.
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Answer: P(0, 5) or P(0, – 1)
Centre = midpoint of AB = (1, 2); radius = ( 4 − 1 ) 2 + ( 1 − 2 ) 2 = 10 . Let P = (0, y). Then ( 0 − 1 ) 2 + ( y − 2 ) 2 = 10 . ( y − 2 ) 2 = 9 ⇒ y = 5 or y = − 1 .So P is (0, 5) or (0, – 1), depending on which side of AB the semi-circle lies.
The vertices of a △ A B C are A(–1, 3), B(2, –3) and C(4, 5). Find the coordinates of a point P on median AD such that AP : PD = 2 : 3.
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Answer: P( 5 3 , 5 11 )
D is the midpoint of BC: D = ( 2 2 + 4 , 2 − 3 + 5 ) = ( 3 , 1 ) . P divides AD in the ratio 2 : 3. P = ( 5 2 ( 3 ) + 3 ( − 1 ) , 5 2 ( 1 ) + 3 ( 3 ) ) = ( 5 3 , 5 11 ) .
If A(a, 0), B(1, 1) and C(0, b) form a triangle, right angled at B when joined, then establish a relation between a and b.
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Answer: a + b = 2
Right angle at B, so A B 2 + B C 2 = A C 2 . A B 2 = ( 1 − a ) 2 + 1 , B C 2 = 1 + ( b − 1 ) 2 , A C 2 = a 2 + b 2 1 − 2 a + a 2 + 1 + 1 + b 2 − 2 b + 1 = a 2 + b 2 4 − 2 a − 2 b = 0 , so a + b = 2
In the given figure, PQ is a tangent to a circle with centre O(−5, 3). If coordinates of P and Q are (3, 1) and (0, 6) respectively, then using distance formula, show that PQ ⊥ OQ.
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Answer: Proved: O Q 2 + P Q 2 = 34 + 34 = 68 = O P 2 , so ∠ O QP = 9 0 ∘ .
O Q 2 = ( 0 + 5 ) 2 + ( 6 − 3 ) 2 = 25 + 9 = 34 P Q 2 = ( 3 − 0 ) 2 + ( 1 − 6 ) 2 = 9 + 25 = 34 O P 2 = ( 3 + 5 ) 2 + ( 1 − 3 ) 2 = 64 + 4 = 68 O Q 2 + P Q 2 = O P 2 , so by the converse of Pythagoras theorem ∠ O QP = 9 0 ∘ , i.e. PQ ⊥ OQ.
The coordinates of the centre of a circle are ( x − 7 , 2 x ) . Find the value(s) of 'x ', if the circle passes through the point ( − 9 , 11 ) and has radius 5 2 units.
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Answer: x = 3 or x = 5
Distance of ( − 9 , 11 ) from the centre equals the radius. ( x − 7 + 9 ) 2 + ( 2 x − 11 ) 2 = ( 5 2 ) 2 = 50 ( x + 2 ) 2 + ( 2 x − 11 ) 2 = 50 x 2 + 4 x + 4 + 4 x 2 − 44 x + 121 = 50 5 x 2 − 40 x + 75 = 0 , i.e. x 2 − 8 x + 15 = 0 ( x − 3 ) ( x − 5 ) = 0 , so x = 3 or x = 5 .
Do the points P ( 1 , 0 ) , Q ( − 5 , 0 ) and R ( − 2 , 5 ) form a triangle ? If so, name the type of triangle formed.
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Answer: Yes; an isosceles triangle (
P R = QR = 34 ,
P Q = 6 ).
P Q = ( 1 + 5 ) 2 + 0 2 = 6 .QR = ( − 2 + 5 ) 2 + ( 5 − 0 ) 2 = 9 + 25 = 34 .P R = ( − 2 − 1 ) 2 + ( 5 − 0 ) 2 = 9 + 25 = 34 .The sum of any two sides exceeds the third (e.g. 2 34 > 6 ; also P, Q lie on the x -axis but R does not), so the points are not collinear and form a triangle. Since QR = P R , it is an isosceles triangle.
If the points A(4, 5), B(m, 6), C(4, 3) and D(1, n) taken in this order are the vertices of a parallelogram ABCD, then find the values of m and n.
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Answer: m = 7, n = 2
The diagonals of a parallelogram bisect each other, so mid-point of AC = mid-point of BD. Mid-point of AC = ( 2 4 + 4 , 2 5 + 3 ) = ( 4 , 4 ) Mid-point of BD = ( 2 m + 1 , 2 6 + n ) 2 m + 1 = 4 ⇒ m = 7 ; 2 6 + n = 4 ⇒ n = 2
If the distance between the points (4, p) and (1, 0) is 5, what is the value of p ?
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Answer: p = ± 4
By the distance formula, ( 4 − 1 ) 2 + ( p − 0 ) 2 = 5 2 . 9 + p 2 = 25 p 2 = 16 , so p = 4 or p = − 4 .
Diagonals AC and BD of square ABCD intersect at P. Coordinates of points B and D are (9, – 2) and (1, 6) respectively. (i) Find the co-ordinates of point P. (ii) Find the length of the side of the square.
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Answer: (i) P(5, 2) (ii) 8 units
(i) Diagonals of a square bisect each other, so P is the midpoint of BD P = ( 2 9 + 1 , 2 − 2 + 6 ) = ( 5 , 2 ) (ii) BD = ( 9 − 1 ) 2 + ( − 2 − 6 ) 2 = 128 = 8 2 Diagonal = 2 × side, so side = 2 8 2 = 8 units
Find the coordinates of a point on the line x + y = 5 which is equidistant from (6, 4) and (5, 2).
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Answer: ( − 2 3 , 2 13 )
Let the point be ( x , y ) ( x − 6 ) 2 + ( y − 4 ) 2 = ( x − 5 ) 2 + ( y − 2 ) 2 − 12 x + 36 − 8 y + 16 = − 10 x + 25 − 4 y + 4 , so 2 x + 4 y = 23 With y = 5 − x : 2 x + 20 − 4 x = 23 , so x = − 2 3 , y = 2 13 Point: ( − 2 3 , 2 13 )
Vertices of a right triangle ABC with ∠ B = 9 0 ∘ are A ( 3 , 4 ) , B ( 1 , 1 ) and C ( − 8 , 7 ) . Find the value of tan A.
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Answer: tan A = 3
A B = ( 3 − 1 ) 2 + ( 4 − 1 ) 2 = 4 + 9 = 13 B C = ( 1 + 8 ) 2 + ( 1 − 7 ) 2 = 81 + 36 = 117 = 3 13 In right △ A B C with ∠ B = 9 0 ∘ : tan A = A B B C = 13 3 13 = 3
Using distance formula, prove that the points A ( 2 , 3 ) , B ( − 7 , 0 ) and C ( − 1 , 2 ) are collinear.
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Answer: Proved.
A B = ( 2 + 7 ) 2 + ( 3 − 0 ) 2 = 81 + 9 = 90 = 3 10 B C = ( − 1 + 7 ) 2 + ( 2 − 0 ) 2 = 36 + 4 = 40 = 2 10 A C = ( 2 + 1 ) 2 + ( 3 − 2 ) 2 = 9 + 1 = 10 B C + C A = 2 10 + 10 = 3 10 = A B Hence A, B, C are collinear (C lies between A and B).
In the given figure, point D divides the side BC of △ A B C in the ratio 1 : 2. Find length AD.
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Answer: AD =
3 130 units (≈ 3.80 units)
From the figure: A ( 1 , 5 ) , B ( − 2 , 1 ) , C ( 4 , 2 ) ; BD : DC = 1 : 2. D = ( 1 + 2 1 ( 4 ) + 2 ( − 2 ) , 1 + 2 1 ( 2 ) + 2 ( 1 ) ) = ( 0 , 3 4 ) A D = ( 1 − 0 ) 2 + ( 5 − 3 4 ) 2 = 1 + 9 121 = 9 130 = 3 130 units
Point P( x , 0 ) divides the line segment joining the points ( 2 , 8 ) and ( − 3 , − 5 ) in a certain ratio. Find the ratio and hence find the value of x .
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Answer: 8 : 5; x = − 13 14
Let P divide the segment in the ratio k : 1 . y -coordinate: k + 1 − 5 k + 8 = 0 , so k = 5 8 ; the ratio is 8 : 5.x = 8 + 5 8 × ( − 3 ) + 5 × 2 = 13 − 24 + 10 = − 13 14 .
Find the ratio in which point P ( − 1 , m ) divides the line segment joining the points A( 2 , 5 ) and B( − 5 , − 2 ) . Hence, find the value of m .
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Answer: 3 : 4; m = 2
Let P divide AB in the ratio k : 1 . x -coordinate: k + 1 − 5 k + 2 = − 1 , so − 5 k + 2 = − k − 1 and k = 4 3 ; ratio 3 : 4.m = 3 + 4 3 × ( − 2 ) + 4 × 5 = 7 14 = 2 .
Find the ratio in which the segment joining the points ( 2 , − 5 ) and ( 5 , 3 ) is divided by x -axis. Also, find coordinates of the point on x -axis.
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Answer: 5 : 3; ( 8 31 , 0 )
Let the x -axis divide the segment in the ratio k : 1 at a point ( x , 0 ) . k + 1 3 k − 5 = 0 , so k = 3 5 ; ratio 5 : 3.x = 5 + 3 5 × 5 + 3 × 2 = 8 31 , so the point is ( 8 31 , 0 ) .
Find the coordinates of the points of trisection of line segment joining the points (–4, 1) and (6, 5).
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Answer: ( − 3 2 , 3 7 ) and ( 3 8 , 3 11 )
Let A(–4, 1), B(6, 5). The points of trisection divide AB in the ratios 1 : 2 and 2 : 1. For 1 : 2: ( 3 1 × 6 + 2 × ( − 4 ) , 3 1 × 5 + 2 × 1 ) = ( − 3 2 , 3 7 ) . For 2 : 1: ( 3 2 × 6 + 1 × ( − 4 ) , 3 2 × 5 + 1 × 1 ) = ( 3 8 , 3 11 ) .
Using distance formula, prove that the points (1, 5), (2, 3) and (3, 1) are collinear.
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Answer: Proved.
Let A(1, 5), B(2, 3), C(3, 1). A B = 1 2 + ( − 2 ) 2 = 5 , B C = 1 2 + ( − 2 ) 2 = 5 .A C = 2 2 + ( − 4 ) 2 = 20 = 2 5 .A B + B C = 2 5 = A C , so A, B, C are collinear.
Establish a relation between x and y such that point (x , y) is equidistant from points (–2, 5) and (3, 9).
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Answer: 10 x + 8 y = 61 (i.e. 10 x + 8 y − 61 = 0 )
Let P(x , y) be equidistant from A(–2, 5) and B(3, 9), so P A 2 = P B 2 . ( x + 2 ) 2 + ( y − 5 ) 2 = ( x − 3 ) 2 + ( y − 9 ) 2 .x 2 + 4 x + 4 + y 2 − 10 y + 25 = x 2 − 6 x + 9 + y 2 − 18 y + 81 .4 x − 10 y + 29 = − 6 x − 18 y + 90 , so 10 x + 8 y − 61 = 0 .
Using distance formula, show that the points (–1, 3), (6, 2) and (3, –1) are vertices of a right-angled triangle.
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Answer: Proved (right angle at (3, –1)).
Let A(–1, 3), B(6, 2), C(3, –1). A B 2 = ( 6 + 1 ) 2 + ( 2 − 3 ) 2 = 49 + 1 = 50 .B C 2 = ( 3 − 6 ) 2 + ( − 1 − 2 ) 2 = 9 + 9 = 18 .A C 2 = ( 3 + 1 ) 2 + ( − 1 − 3 ) 2 = 16 + 16 = 32 .B C 2 + A C 2 = 18 + 32 = 50 = A B 2 , so by the converse of Pythagoras theorem, △ A B C is right-angled at C.
The coordinates of the centre of a circle are ( 2 a , a − 7 ) . Find the value(s) of 'a' if the circle passes through the point ( 11 , − 9 ) and has diameter 10 2 units.
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Answer: a = 3 or a = 5
Radius = 5 2 , so (radius)2 = 50 . Distance from centre ( 2 a , a − 7 ) to ( 11 , − 9 ) equals the radius: ( 11 − 2 a ) 2 + ( − 9 − a + 7 ) 2 = 50 ( 11 − 2 a ) 2 + ( a + 2 ) 2 = 50 121 − 44 a + 4 a 2 + a 2 + 4 a + 4 = 50 5 a 2 − 40 a + 75 = 0 , i.e. a 2 − 8 a + 15 = 0 ( a − 3 ) ( a − 5 ) = 0 , so a = 3 or a = 5 .
Find the length of the median through the vertex B of △ A B C with vertices A ( 9 , − 2 ) , B ( − 3 , 7 ) and C ( − 1 , 10 ) .
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The median through B joins B to the mid-point D of A C . D = ( 2 9 + ( − 1 ) , 2 − 2 + 10 ) = ( 4 , 4 ) .B D = ( 4 + 3 ) 2 + ( 4 − 7 ) 2 = 49 + 9 = 58 units.
Find the coordinates of the point C which lies on the line AB produced such that A C = 2 B C , where coordinates of points A and B are ( − 1 , 7 ) and ( 4 , − 3 ) respectively.
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Answer: C ( 9 , − 13 )
C lies on AB produced beyond B and A C = 2 B C , so A B = A C − B C = B C : B is the mid-point of AC. Let C = ( x , y ) . Then 2 − 1 + x = 4 and 2 7 + y = − 3 x = 9 , y = − 13 , so C = ( 9 , − 13 )
The coordinates of the end points of the line segment AB are A ( − 2 , − 2 ) and B ( 2 , − 4 ) . P is the point on AB such that B P = 7 4 A B . Find the coordinates of point P.
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Answer: P ( − 7 2 , − 7 20 )
B P = 7 4 A B ⇒ A P = 7 3 A B , so A P : P B = 3 : 4 .x = 7 3 ( 2 ) + 4 ( − 2 ) = − 7 2 y = 7 3 ( − 4 ) + 4 ( − 2 ) = − 7 20 P ( − 7 2 , − 7 20 )
Prove that abscissa of a point P which is equidistant from points with coordinates A ( 7 , 1 ) and B ( 3 , 5 ) is 2 more than its ordinate.
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Answer: Proved.
Let P ( x , y ) . P A = P B ⇒ P A 2 = P B 2 ( x − 7 ) 2 + ( y − 1 ) 2 = ( x − 3 ) 2 + ( y − 5 ) 2 − 14 x + 49 − 2 y + 1 = − 6 x + 9 − 10 y + 25 − 8 x + 8 y + 16 = 0 ⇒ x − y = 2 So x = y + 2 : the abscissa is 2 more than the ordinate.
If Q ( 0 , 2 ) is equidistant from P ( 5 , − 3 ) and R ( x , 7 ) , find the value(s) of x .
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Answer: x = ± 5
QP = QR , so Q P 2 = Q R 2 .Q P 2 = ( 5 − 0 ) 2 + ( − 3 − 2 ) 2 = 25 + 25 = 50 .Q R 2 = ( x − 0 ) 2 + ( 7 − 2 ) 2 = x 2 + 25 .x 2 + 25 = 50 , so x 2 = 25 and x = ± 5 .
If A ( 1 , 1 ) and B ( 7 , 9 ) are the end points of a diameter of a circle, then find the co-ordinates of the centre of the circle.
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Answer: (4, 5)
The centre is the mid-point of the diameter AB. Centre = ( 2 1 + 7 , 2 1 + 9 ) = ( 4 , 5 ) .
Find the ratio in which the Y-axis divides the line segment joining the points A ( 5 , − 6 ) and B ( − 1 , − 4 ) . Also, find the point of intersection.
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Answer: Ratio 5 : 1; point of intersection ( 0 , − 3 13 )
Let the Y-axis divide AB in the ratio k : 1 . The point is ( k + 1 − k + 5 , k + 1 − 4 k − 6 ) . On the Y-axis the x-coordinate is 0, so − k + 5 = 0 and k = 5 . Ratio = 5 : 1 . y-coordinate = 6 − 20 − 6 = − 3 13 . Point of intersection = ( 0 , − 3 13 ) .
Find a point which is equidistant from the points A ( − 1 , 5 ) and B ( 2 , 1 ) . How many such points are there ?
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Answer: For example ( 2 1 , 3 ) (the mid-point of AB); there are infinitely many such points, all on the line 6 x − 8 y + 21 = 0 .
The mid-point of AB is equidistant from A and B: ( 2 − 1 + 2 , 2 5 + 1 ) = ( 2 1 , 3 ) . In general P ( x , y ) is equidistant if ( x + 1 ) 2 + ( y − 5 ) 2 = ( x − 2 ) 2 + ( y − 1 ) 2 . This simplifies to 6 x − 8 y + 21 = 0 , the perpendicular bisector of AB. Every point on this line works, so there are infinitely many such points.
Point P ( x , y ) divides the line segment joining the points A ( − 1 , 3 ) and B ( 9 , 8 ) such that A P : P B = k : 1 . If the co-ordinates of P are such that x = y , then find the value of k.
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Answer: k = 4
By the section formula, x = k + 1 9 k − 1 and y = k + 1 8 k + 3 . x = y gives 9 k − 1 = 8 k + 3 , so k = 4 .Check: P = (7, 7).
Find the ratio in which the point ( 3 , y ) , divides the line segment joining the points ( − 2 , − 5 ) and ( 6 , 3 ) . Also, find the value of y.
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Answer: Ratio 5 : 3 ; y = 0
Let the point divide the segment in the ratio k : 1 . x-coordinate: k + 1 6 k − 2 = 3 , so 6 k − 2 = 3 k + 3 , giving k = 3 5 . So the ratio is 5 : 3 . y = 5 + 3 5 × 3 + 3 × ( − 5 ) = 8 15 − 15 = 0 .
Find a point on y-axis which is equidistant from the points A ( 6 , 5 ) and B ( − 4 , 3 ) .
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Answer: ( 0 , 9 )
Let the point be P ( 0 , y ) . Then P A 2 = P B 2 . 36 + ( y − 5 ) 2 = 16 + ( y − 3 ) 2 .36 + y 2 − 10 y + 25 = 16 + y 2 − 6 y + 9 .61 − 10 y = 25 − 6 y , so 4 y = 36 and y = 9 .The point is ( 0 , 9 ) .
Find the type of triangle ABC formed whose vertices are A(1, 0), B(− 5 , 0) and C(− 2 , 5).
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Answer: Isosceles triangle (AC = BC =
34 units, AB = 6 units)
A B = ( − 5 − 1 ) 2 + 0 2 = 6 B C = ( − 2 + 5 ) 2 + ( 5 − 0 ) 2 = 9 + 25 = 34 A C = ( − 2 − 1 ) 2 + ( 5 − 0 ) 2 = 9 + 25 = 34 BC = AC, so △ A B C is isosceles. (Also A C 2 + B C 2 = 68 = 36 = A B 2 , so it is not right-angled.)
In what ratio is the line segment joining the points ( 3 , − 5 ) and ( − 1 , 6 ) divided by the line y = x ?
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Answer: 8 : 7
Let the point dividing the segment in the ratio k : 1 be ( k + 1 − k + 3 , k + 1 6 k − 5 ) . It lies on y = x , so − k + 3 = 6 k − 5 . 7 k = 8 , so k = 7 8 .The ratio is 8 : 7.
A(3, 0), B(6, 4) and C(− 1 , 3) are vertices of a triangle ABC. Find length of its median BE.
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E is the mid-point of AC: E = ( 2 3 − 1 , 2 0 + 3 ) = ( 1 , 2 3 ) B E = ( 6 − 1 ) 2 + ( 4 − 2 3 ) 2 = 25 + 4 25 = 4 125 = 2 5 5 units
The vertices of a △ A B C are A(− 2 , 4), B(4, 3) and C(1, − 6 ). Find length of the median BD.
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Answer: BD
= 2 145 units (about 6.02 units)
D is the mid-point of AC: D = ( 2 − 2 + 1 , 2 4 − 6 ) = ( − 2 1 , − 1 ) B D = ( 4 + 2 1 ) 2 + ( 3 + 1 ) 2 = 4 81 + 16 = 4 145 = 2 145 units
In the given figure, a circle centred at origin O has radius 7 cm, OC is median of △ O A B . Find the length of median OC.
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Answer: OC
= 2 7 2 cm (about 4.95 cm)
From the figure, A lies on the negative y-axis and B on the positive x-axis, on the circle of radius 7: A(0, − 7 ), B(7, 0). C is the mid-point of AB: C = ( 2 7 , − 2 7 ) . O C = ( 2 7 ) 2 + ( 2 7 ) 2 = 2 7 2 = 2 7 2 cm ≈ 4.95 cm
Find a relation between x and y such that the point P(x , y) is equidistant from the points A(7, 1) and B(3, 5).
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Answer: x − y = 2
PA = PB, so P A 2 = P B 2 . ( x − 7 ) 2 + ( y − 1 ) 2 = ( x − 3 ) 2 + ( y − 5 ) 2 .x 2 − 14 x + 49 + y 2 − 2 y + 1 = x 2 − 6 x + 9 + y 2 − 10 y + 25 .− 14 x − 2 y + 50 = − 6 x − 10 y + 34 ⇒ − 8 x + 8 y + 16 = 0 .So x − y = 2 .
Points A(− 1 , y) and B(5, 7) lie on a circle with centre O(2, − 3 y ) such that AB is a diameter of the circle. Find the value of y. Also, find the radius of the circle.
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Answer: y = − 1 ; radius = 5 units
O is the mid-point of diameter AB. Mid-point of AB = ( 2 − 1 + 5 , 2 y + 7 ) = ( 2 , 2 y + 7 ) . So 2 y + 7 = − 3 y ⇒ y + 7 = − 6 y ⇒ y = − 1 . Then O = (2, 3) and A = (− 1 , − 1 ). Radius OA = ( 2 + 1 ) 2 + ( 3 + 1 ) 2 = 9 + 16 = 5 units.
Find the ratio in which the point P(–4, 6) divides the line segment joining the points A(–6, 10) and B(3, –8).
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Answer: 2 : 7
Let P divide AB in the ratio k : 1 . x-coordinate: k + 1 3 k − 6 = − 4 ⇒ 3 k − 6 = − 4 k − 4 ⇒ k = 7 2 . Check y: 7 2 + 1 − 8 × 7 2 + 10 = 9/7 54/7 = 6 . ✓ So P divides AB in the ratio 2 : 7.
Prove that the points (3, 0), (6, 4) and (–1, 3) are the vertices of an isosceles triangle.
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Answer: Proved.
Let A(3, 0), B(6, 4), C(–1, 3). A B = 3 2 + 4 2 = 5 , A C = ( − 4 ) 2 + 3 2 = 5 , B C = ( − 7 ) 2 + ( − 1 ) 2 = 50 = 5 2 .AB = AC (and the points are not collinear since A B + A C = 10 = 5 2 ), so ABC is an isosceles triangle.
Find the coordinates of the point which divides the line segment joining the points ( 7 , − 1 ) and ( − 3 , 4 ) internally in the ratio 2 : 3.
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Answer: (3, 1)
Using the section formula with m : n = 2 : 3 : x = 2 + 3 2 ( − 3 ) + 3 ( 7 ) = 5 − 6 + 21 = 3 y = 2 + 3 2 ( 4 ) + 3 ( − 1 ) = 5 8 − 3 = 1 The point is (3, 1).
Find the value(s) of y for which the distance between the points A(3, − 1 ) and B(11, y) is 10 units.
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Answer: y = 5 or y = − 7
A B 2 = ( 11 − 3 ) 2 + ( y + 1 ) 2 = 100 64 + ( y + 1 ) 2 = 100 , so ( y + 1 ) 2 = 36 y + 1 = ± 6 y = 5 or y = − 7
Find the value(s) of ‘x’ so that PQ = QR, where the coordinates of P, Q and R are ( 6 , − 1 ) , ( 1 , 3 ) and ( x , 8 ) respectively.
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Answer: x = 5 or x = − 3
P Q 2 = ( 1 − 6 ) 2 + ( 3 + 1 ) 2 = 25 + 16 = 41 Q R 2 = ( x − 1 ) 2 + ( 8 − 3 ) 2 = ( x − 1 ) 2 + 25 PQ = QR gives ( x − 1 ) 2 + 25 = 41 , so ( x − 1 ) 2 = 16 x − 1 = ± 4 , so x = 5 or x = − 3
The vertices of a triangle are ( − 2 , 0 ) , ( 2 , 3 ) and ( 1 , − 3 ) . Is the triangle equilateral, isosceles or scalene ?
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Answer: Scalene
Let A(−2, 0), B(2, 3), C(1, −3). A B = 4 2 + 3 2 = 5 B C = ( − 1 ) 2 + ( − 6 ) 2 = 37 C A = ( − 3 ) 2 + 3 2 = 18 = 3 2 All three sides are different, so the triangle is scalene.
Find the coordinates of the point which divides the join of A ( − 1 , 7 ) and B ( 4 , − 3 ) in the ratio 2 : 3.
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Answer: ( 1 , 3 )
By the section formula with m : n = 2 : 3 : x = 5 2 ( 4 ) + 3 ( − 1 ) = 5 5 = 1 .y = 5 2 ( − 3 ) + 3 ( 7 ) = 5 15 = 3 .The point is ( 1 , 3 ) .
If the points A ( 2 , 3 ) , B ( − 5 , 6 ) , C ( 6 , 7 ) and D ( p , 4 ) are the vertices of a parallelogram ABCD, find the value of p .
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Answer: p = 13
Diagonals of a parallelogram bisect each other, so the mid-points of AC and BD coincide. Mid-point of AC = ( 2 2 + 6 , 2 3 + 7 ) = ( 4 , 5 ) . Mid-point of BD = ( 2 − 5 + p , 2 6 + 4 ) = ( 2 p − 5 , 5 ) . 2 p − 5 = 4 ⇒ p = 13 .
Show that A(1, 2), B(5, 4), C(3, 8) and D(− 1, 6) are vertices of a parallelogram ABCD.
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Answer: Proved.
AB = 4 2 + 2 2 = 20 , CD = ( − 4 ) 2 + ( − 2 ) 2 = 20 . BC = ( − 2 ) 2 + 4 2 = 20 , DA = 2 2 + ( − 4 ) 2 = 20 . Both pairs of opposite sides are equal (AB = CD and BC = DA), so ABCD is a parallelogram. (Check: midpoint of AC = (2, 5) = midpoint of BD, so the diagonals bisect each other.)
Show that the points A(3, 0), B(6, 4) and C(− 1, 3) are vertices of a right-angled triangle.
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Answer: Proved.
A B 2 = ( 6 − 3 ) 2 + ( 4 − 0 ) 2 = 25 .A C 2 = ( − 1 − 3 ) 2 + ( 3 − 0 ) 2 = 25 .B C 2 = ( − 1 − 6 ) 2 + ( 3 − 4 ) 2 = 50 .A B 2 + A C 2 = 50 = B C 2 , so by the converse of Pythagoras theorem the triangle is right-angled at A.
Show that the points ( − 2 , 3 ) , ( 8 , 3 ) and ( 6 , 7 ) are the vertices of a right-angled triangle.
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Answer: Proved.
Let A( − 2 , 3 ) , B( 8 , 3 ) , C( 6 , 7 ) . A B 2 = 1 0 2 + 0 2 = 100 B C 2 = ( − 2 ) 2 + 4 2 = 20 A C 2 = 8 2 + 4 2 = 80 B C 2 + A C 2 = 20 + 80 = 100 = A B 2 , so by the converse of Pythagoras theorem the triangle is right-angled at C.
The line segment joining the points A ( 4 , − 5 ) and B ( 4 , 5 ) is divided by the point P such that AP : AB = 2 : 5. Find the coordinates of P.
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Answer: P(4, − 1 )
AP : AB = 2 : 5, so AP : PB = 2 : 3. x = 5 2 × 4 + 3 × 4 = 4 .y = 5 2 × 5 + 3 × ( − 5 ) = 5 − 5 = − 1 .P is (4, − 1 ).
Point P(x, y) is equidistant from points A(5, 1) and B(1, 5). Prove that x = y.
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Answer: Proved.
PA = PB, so P A 2 = P B 2 . ( x − 5 ) 2 + ( y − 1 ) 2 = ( x − 1 ) 2 + ( y − 5 ) 2 .x 2 − 10 x + 25 + y 2 − 2 y + 1 = x 2 − 2 x + 1 + y 2 − 10 y + 25 .− 10 x − 2 y = − 2 x − 10 y , so − 8 x = − 8 y .Hence x = y.
Find the ratio in which y-axis divides the line segment joining the points ( 5 , − 6 ) and ( − 1 , − 4 ) .
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Answer: 5 : 1 (point of division ( 0 , − 3 13 ) )
Let the y-axis divide the segment in the ratio k : 1. The point has x-coordinate 0. k + 1 k ( − 1 ) + 1 ( 5 ) = 0 , so k = 5.Ratio = 5 : 1. y-coordinate = 6 5 ( − 4 ) + 1 ( − 6 ) = − 3 13 .
Find the ratio in which line y = x divides the line segment joining the points ( 6 , − 3 ) and ( 1 , 6 ) .
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Answer: 9 : 5
Let the line divide the segment in the ratio k : 1. Point of division = ( k + 1 k + 6 , k + 1 6 k − 3 ) . It lies on y = x : 6 k − 3 = k + 6 , so 5 k = 9 , k = 5 9 . Ratio = 9 : 5 (point of division ( 14 39 , 14 39 ) ).
A line intersects y-axis and x-axis at point P and Q, respectively. If R(2, 5) is the mid-point of line segment PQ, then find the coordinates of P and Q.
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Answer: P(0, 10) and Q(4, 0)
Let P = (0, b) on the y-axis and Q = (a, 0) on the x-axis. Mid-point of PQ = ( 2 a , 2 b ) = ( 2 , 5 ) . So a = 4 and b = 10. P = (0, 10), Q = (4, 0).
Find the points on the x -axis, each of which is at a distance of 10 units from the point A(11, – 8).
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Answer: (17, 0) and (5, 0)
Let the point be P(x, 0). P A 2 = ( x − 11 ) 2 + ( 0 + 8 ) 2 = 100 ( x − 11 ) 2 = 36 , so x − 11 = ± 6 .x = 17 or x = 5. The points are (17, 0) and (5, 0).
Find the ratio in which the y-axis divides the line segment joining the points (5, – 6) and (–1, – 4).
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Answer: 5 : 1
Let the y-axis divide the segment in the ratio k : 1 at (0, y). x-coordinate: k + 1 k ( − 1 ) + 1 ( 5 ) = 0 − k + 5 = 0 , so k = 5.Ratio = 5 : 1
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