NCERT Exemplar Solutions
Class 10 - Mathematics
CHAPTER 7: Coordinate Geometry

NCERT Exemplar Class 10 Mathematics Unit 7 (Coordinate Geometry) complete answers and solutions.

Exercise 7.1

Coordinate Geometry MCQs: distance formula, section formula, rectangles/triangles, perpendicular bisectors.

Question.  1

The distance of the point \(P(2,3)\) from the x-axis is

(A)

2

(B)

3

(C)

1

(D)

5

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Question.  2

The distance between the points \(A(0,6)\) and \(B(0,-2)\) is

(A)

6

(B)

8

(C)

4

(D)

2

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Question.  3

The distance of the point \(P(-6,8)\) from the origin is

(A)

8

(B)

\(2\sqrt{7}\)

(C)

10

(D)

6

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Question.  4

The distance between the points \((0,5)\) and \((-5,0)\) is

(A)

5

(B)

\(5\sqrt{2}\)

(C)

\(2\sqrt{5}\)

(D)

10

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Question.  5

AOBC is a rectangle whose three vertices are \(A(0,3),\ O(0,0)\) and \(B(5,0)\). The length of its diagonal is

(A)

5

(B)

3

(C)

\(\sqrt{34}\)

(D)

4

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Question.  6

The perimeter of a triangle with vertices \((0,4),(0,0),(3,0)\) is

(A)

5

(B)

12

(C)

11

(D)

\(7+\sqrt{5}\)

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Question.  7

The area of a triangle with vertices \(A(3,0),\ B(7,0)\) and \(C(8,4)\) is

(A)

14

(B)

28

(C)

8

(D)

6

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Question.  8

The points \((-4,0),(4,0)\) and \((0,3)\) are the vertices of a

(A)

right triangle

(B)

isosceles triangle

(C)

equilateral triangle

(D)

scalene triangle

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Question.  9

The point which divides the line segment joining \((7,-6)\) and \((3,4)\) in ratio \(1:2\) internally lies in the

(A)

I quadrant

(B)

II quadrant

(C)

III quadrant

(D)

IV quadrant

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Question.  10

The point which lies on the perpendicular bisector of the line segment joining the points \(A(-2,-5)\) and \(B(2,5)\) is

(A)

(0, 0)

(B)

(0, 2)

(C)

(2, 0)

(D)

(-2, 0)

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Question.  11

The fourth vertex \(D\) of a parallelogram \(ABCD\) whose three vertices are \(A(-2,3),\ B(6,7)\) and \(C(8,3)\) is

(A)

(0, 1)

(B)

(0, -1)

(C)

(-1, 0)

(D)

(1, 0)

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Question.  12

If the point \(P(2,1)\) lies on the line segment joining points \(A(4,2)\) and \(B(8,4)\), then

(A)

\(AP=\dfrac{1}{3}\,AB\)

(B)

\(AP=PB\)

(C)

\(PB=\dfrac{1}{3}\,AB\)

(D)

\(AP=\dfrac{1}{2}\,AB\)

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Question.  13

If \(P\big(\dfrac{a}{3},4\big)\) is the mid-point of the line segment joining the points \(Q(-6,5)\) and \(R(-2,3)\), then the value of \(a\) is

(A)

-4

(B)

-12

(C)

12

(D)

-6

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Question.  14

The perpendicular bisector of the line segment joining the points \(A(1,5)\) and \(B(4,6)\) cuts the y-axis at

(A)

(0, 13)

(B)

(0, -13)

(C)

(0, 12)

(D)

(13, 0)

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Question.  15

The coordinates of the point which is equidistant from the three vertices of \(\triangle AOB\) as shown in Fig. 7.1 is

Fig. 7.1

(A)

(x, y)

(B)

(y, x)

(C)

\(\big(\dfrac{x}{2},\dfrac{y}{2}\big)\)

(D)

\(\big(\dfrac{y}{2},\dfrac{x}{2}\big)\)

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Question.  16

A circle drawn with origin as the centre passes through \(\big(\dfrac{13}{2},0\big)\). The point which does not lie in the interior of the circle is

(A)

\(\big(-\dfrac{3}{4},1\big)\)

(B)

\(\big(2,\dfrac{7}{3}\big)\)

(C)

\(\big(5,-\dfrac{1}{2}\big)\)

(D)

\(\big(-6,\dfrac{5}{2}\big)\)

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Question.  17

A line intersects the y-axis and x-axis at the points \(P\) and \(Q\), respectively. If \((2,-5)\) is the mid-point of \(PQ\), then the coordinates of \(P\) and \(Q\) are, respectively

(A)

(0, -5) and (2, 0)

(B)

(0, 10) and (-4, 0)

(C)

(0, 4) and (-10, 0)

(D)

(0, -10) and (4, 0)

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Question.  18

The area of a triangle with vertices \((a,b+c)\), \((b,c+a)\) and \((c,a+b)\) is

(A)

\((a+b+c)^2\)

(B)

0

(C)

\(a+b+c\)

(D)

\(abc\)

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Question.  19

If the distance between the points \((4,p)\) and \((1,0)\) is 5, then the value of \(p\) is

(A)

4 only

(B)

\(\pm 4\)

(C)

-4 only

(D)

0

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Question.  20

If the points \(A(1,2)\), \(O(0,0)\) and \(C(a,b)\) are collinear, then

(A)

\(a=b\)

(B)

\(a=2b\)

(C)

\(2a=b\)

(D)

\(a=-b\)

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Exercise 7.2

True/False with justification in coordinate geometry.

Question. 1

\(\triangle ABC\) with vertices \(A(-2,0),\ B(2,0),\ C(0,2)\) is similar to \(\triangle DEF\) with vertices \(D(-4,0),\ E(4,0),\ F(0,4)\).

Answer:

True.

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Question. 2

Point \(P(-4,2)\) lies on the line segment joining \(A(-4,6)\) and \(B(-4,-6)\).

Answer:

True.

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Question. 3

The points \((0,5),\ (0,-9),\ (3,6)\) are collinear.

Answer:

False.

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Question. 4

\(P(0,2)\) is the intersection of the y–axis and the perpendicular bisector of the segment joining \(A(-1,1)\) and \(B(3,3)\).

Answer:

False.

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Question. 5

Points \(A(3,1),\ B(12,-2),\ C(0,2)\) cannot be vertices of a triangle.

Answer:

True.

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Question. 6

Points \(A(4,3),\ B(6,4),\ C(5,-6),\ D(-3,5)\) are vertices of a parallelogram.

Answer:

False.

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Question. 7

A circle has centre at the origin and a point \(P(5,0)\) lies on it. The point \(Q(6,8)\) lies outside the circle.

Answer:

True.

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Question. 8

The point \(A(2,7)\) lies on the perpendicular bisector of the segment joining \(P(6,5)\) and \(Q(0,-4)\).

Answer:

False.

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Question. 9

The point \(P(5,-3)\) is one of the two trisection points of the segment joining \(A(7,-2)\) and \(B(1,-5)\).

Answer:

True.

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Question. 10

Points \(A(-6,10),\ B(-4,6),\ C(3,-8)\) are collinear such that \(AB=\dfrac{2}{9}\,AC\).

Answer:

True.

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Question. 11

The point \(P(-2,4)\) lies on a circle of radius 6 and centre \((3,5)\).

Answer:

False.

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Question. 12

The points \(A(-1,-2),\ B(4,3),\ C(2,5),\ D(-3,0)\) in that order form a rectangle.

Answer:

True.

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Exercise 7.3

Coordinate geometry short problems with worked answers.

Question. 1

Name the type of triangle formed by the points \(A(-5,6),\ B(-4,-2),\ C(7,5)\).

Answer:

Scalene.

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Question. 2

Find the point(s) on the x–axis at a distance \(2\sqrt5\) from \((7,-4)\). How many such points are there?

Answer:

(5, 0) and (9, 0) — two points.

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Question. 3

What type of quadrilateral is formed by the points \(A(2,-2),\ B(7,3),\ C(11,-1),\ D(6,-6)\) in order?

Answer:

Rectangle.

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Question. 4

Find \(a\) if the distance between \(A(-3,-14)\) and \(B(a,-5)\) is \(9\).

Answer:

\(a=-3\)

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Question. 5

Find a point equidistant from \(A(-5,4)\) and \(B(-1,6)\). How many such points are there?

Answer:

One example is (-3, 5). There are infinitely many such points (on the perpendicular bisector).

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Question. 6

Find the coordinates of the point \(Q\) on the x–axis which lies on the perpendicular bisector of the segment joining \(A(-5,-2)\) and \(B(4,-2)\). Also, name the type of triangle formed by \(Q, A, B\).

Answer:

\(Q = \left(-\dfrac{1}{2}, 0\right)\)

Triangle \(QAB\) is isosceles (\(QA=QB\)).

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Question. 7

Find \(m\) if the points \((5,1),\ (-2,-3),\ (8,2m)\) are collinear.

Answer:

\(m=\dfrac{19}{14}\)

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Question. 8

If \(A(2,-4)\) is equidistant from \(P(3,8)\) and \(Q(-10,y)\), find \(y\). Also find \(PQ\).

Answer:

\(y=-3\) or \(y=-5\)

\(PQ=\sqrt{290}\) when \(y=-3\); and \(PQ=13\sqrt{2}\) when \(y=-5\).

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Question. 9

Find the area of the triangle with vertices \((-8,4),\ (-6,6),\ (-3,9)\).

Answer:

0

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Question. 10

In what ratio does the x–axis divide the segment joining \((-4,-6)\) and \((-1,7)\)? Find the coordinates of the point of division.

Answer:

Ratio \(6:7\) (internally), point \(\big(-\dfrac{34}{13},\,0\big)\).

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Question. 11

Find the ratio in which the point \(P\big(\dfrac{3}{4},\dfrac{5}{12}\big)\) divides the segment joining \(A\big(\dfrac{1}{2},\dfrac{3}{2}\big)\) and \(B(2,-5)\).

Answer:

\(1:5\) (\(AP:PB\)).

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Question. 12

If \(P(9a-2,-b)\) divides the segment joining \(A(3a+1,-3)\) and \(B(8a,5)\) in the ratio \(3:1\), find \(a\) and \(b\).

Answer:

\(a=1,\ b=-3\)

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Question. 13

If \((a,b)\) is the midpoint of the segment joining \(A(10,-6)\) and \(B(k,4)\) and \(a-2b=18\), find \(k\) and \(|AB|\).

Answer:

\(k=22\), \(|AB|=2\sqrt{61}\)

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Question. 14

The centre of a circle is \((2a,\,a-7)\). If it passes through \((11,-9)\) and has diameter \(10\sqrt2\), find \(a\).

Answer:

\(a=3\) or \(a=5\)

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Question. 15

The line segment joining the points \(A(3,2)\) and \(B(5,1)\) is divided at the point \(P\) in the ratio \(1:2\), and \(P\) lies on the line \(3x - 18y + k = 0\). Find the value of \(k\).

Answer:

\(k=19\)

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Question. 16

If \(D\big(-\dfrac{1}{2},\dfrac{5}{2}\big),\ E(7,3),\ F\big(\dfrac{7}{2},\dfrac{7}{2}\big)\) are the midpoints of the sides of \(\triangle ABC\), find \(\text{area}(\triangle ABC)\).

Answer:

\(11\) square units.

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Question. 17

The points \(A(2,9),\ B(a,5),\ C(5,5)\) are vertices of a triangle right–angled at \(B\). Find \(a\) and the area of \(\triangle ABC\).

Answer:

\(a=2\), area \(=6\).

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Question. 18

Find the coordinates of the point \(R\) on the segment joining \(P(-1,3)\) and \(Q(2,5)\) such that \(PR=\dfrac{3}{5}PQ\).

Answer:

\(R\big(\dfrac{4}{5},\dfrac{21}{5}\big)\)

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Question. 19

Find \(k\) if the points \(A(k+1,2k),\ B(3k,2k+3),\ C(5k-1,5k)\) are collinear.

Answer:

\(k=2\)

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Question. 20

Find the ratio in which the line \(2x+3y-5=0\) divides the segment joining \(B(8,-9)\) and \(C(2,1)\). Also find the coordinates of the point of division.

Answer:

Ratio \(8:1\) (internally, from \(B:C\)). Point \(\big(\dfrac{8}{3},\,-\dfrac{1}{9}\big)\).

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Exercise 7.4

Coordinate geometry applications: special triangles, parallelogram properties, section formula, centroid, loci, and distance computations.

Question. 1

If \((-4,\,3)\) and \((4,\,3)\) are two vertices of an equilateral triangle, find the coordinates of the third vertex, given that the origin lies in the interior of the triangle.

Answer:

The third vertex is \(\bigl(0,\;3-4\sqrt{3}\bigr).\)

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Question. 2

\(A(6,1),\ B(8,2)\) and \(C(9,4)\) are three vertices of a parallelogram \(ABCD\). If \(E\) is the midpoint of \(DC\), find the area of \(\triangle ADE\).

Answer:

Area \(= \dfrac{3}{4}\) square units.

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Question. 3

The points \(A(x_1,y_1),\ B(x_2,y_2)\) and \(C(x_3,y_3)\) are the vertices of \(\triangle ABC\).

(i) The median from \(A\) meets \(BC\) at \(D\). Find \(D\).

(ii) Find the point \(P\) on \(AD\) such that \(AP:PD=2:1\).

(iii) Find points \(Q\) and \(R\) on medians \(BE\) and \(CF\) respectively such that \(BQ:QE=2:1\) and \(CR:RF=2:1\).

(iv) Hence, write the coordinates of the centroid of \(\triangle ABC\).

Answer:

(i) \(D\bigl(\dfrac{x_2+x_3}{2},\;\dfrac{y_2+y_3}{2}\bigr)\).

(ii) \(P\bigl(\dfrac{x_1+x_2+x_3}{3},\;\dfrac{y_1+y_2+y_3}{3}\bigr)\).

(iii) \(Q\) and \(R\) are also \(\bigl(\dfrac{x_1+x_2+x_3}{3},\;\dfrac{y_1+y_2+y_3}{3}\bigr)\).

(iv) Centroid \(G\bigl(\dfrac{x_1+x_2+x_3}{3},\;\dfrac{y_1+y_2+y_3}{3}\bigr)\).

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Question. 4

The points \(A(1,-2),\ B(2,3),\ C(a,2)\) and \(D(-4,-3)\) form a parallelogram. Find \(a\) and the height of the parallelogram taking \(AB\) as the base.

Answer:

\(a=-3\) and the height (on base \(AB\)) is \(\dfrac{24}{\sqrt{26}}\).

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Question. 5

Students stand on a grid for drill. Points \(A, B, C, D\) are shown below. Is it possible to place Jaspal so that he is equidistant from all four? If yes, give his position.

Fig. 7.4 (grid with A, B, C, D)

(Use grid coordinates: \(A(3,5),\ B(6,8),\ C(10,5),\ D(7,1)\).)

Answer:

Yes. Jaspal should stand at \(\bigl(6.5,\,4.5\bigr)\).

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Question. 6

Ayush travels House \(\to\) Bank \(\to\) School \(\to\) Office along straight segments instead of going directly House \(\to\) Office. If \(H(2,4),\ B(5,8),\ S(13,14),\ O(13,26)\), find the extra distance travelled.

Answer:

Extra distance \(= 27 - \sqrt{605}\;\text{km} \approx 2.404\;\text{km}.\)

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NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 7: Coordinate Geometry | Detailed Answers