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NCERT Class 10 Mathematics Exercise 7.2 Solutions: Coordinate Geometry
AI-written, checked on 23 Oct 2026
Solutions written by Shishya, checked — not the board's official answers
Step-by-step working for every question of Exercise 7.2 in NCERT's Class 10 Mathematics book, chapter “Coordinate Geometry”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.
How these were checked: the solutions were drafted with AI and then read and corrected on 23 Oct 2026. Every numerical final answer is recomputed from the question's own numbers by a calculator check that runs before each release; proofs and explanations were read, not machine-checked. The NCERT textbook is the authority — if something here disagrees with it, follow the book.
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Ex 7.2 Q1
Find the point dividing the join of (−1, 7) and (4, −3) in the ratio 2 : 3.
- Identify the coordinates of the two points as A(−1, 7) and B(4, −3).
- Note that the point P divides the segment AB in the ratio m : n = 2 : 3.
- Apply the section formula for the x-coordinate: x = (m x₂ + n x₁) / (m + n).
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- Substitute the values into the x-coordinate formula: x = (2 × 4 + 3 × (−1)) / (2 + 3).
why?
Putting the known values in place of the letters turns the formula or equation into plain arithmetic — the letters stood for exactly these values.
- Calculate the numerator and denominator for x: x = (8 − 3) / 5 = 5 / 5 = 1.
- Apply the section formula for the y-coordinate: y = (m y₂ + n y₁) / (m + n).
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- Substitute the values into the y-coordinate formula: y = (2 × (−3) + 3 × 7) / (2 + 3).
why?
Putting the known values in place of the letters turns the formula or equation into plain arithmetic — the letters stood for exactly these values.
- Calculate the numerator and denominator for y: y = (−6 + 21) / 5 = 15 / 5 = 3.
- Combine the calculated coordinates to find the point P(1, 3).
Answer: (1, 3)
Ex 7.2 Q2
Find the points of trisection of the segment joining (4, −1) and (−2, −3).
- Let A be (4, -1) and B be (-2, -3).
- The points of trisection divide AB in the ratio 1:2 and 2:1.
- Let P be the point closer to A, so AP:PB = 1:2.
- Using the section formula, the x-coordinate of P is (1 × (-2) + 2 × 4) / (1 + 2) = 6/3 = 2.
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- The y-coordinate of P is (1 × (-3) + 2 × (-1)) / (1 + 2) = -5/3.
- So, P is (2, -5/3).
- Let Q be the point closer to B, so AQ:QB = 2:1.
- Using the section formula, the x-coordinate of Q is (2 × (-2) + 1 × 4) / (2 + 1) = 0/3 = 0.
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- The y-coordinate of Q is (2 × (-3) + 1 × (-1)) / (2 + 1) = -7/3.
- So, Q is (0, -7/3).
Answer: The points of trisection are (2, -5/3) and (0, -7/3).
Ex 7.2 Q3
On a school ground with lines 1 m apart and 100 pots 1 m apart along AD (Fig. 7.12), Niharika posts a green flag 1/4 of AD along the 2nd line and Preet a red flag 1/5 of AD along the 8th line. How far apart are the flags, and where should Rashmi post a blue flag halfway between them?
Uses a figure printed in the NCERT book — open the chapter above to see it.
- Let the length of AD be 100 m, so the 2nd line is at x = 2 and the 8th line is at x = 8.
- Niharika's green flag is at 1/4 of AD along the 2nd line, so its coordinates are (2, 25).
- Preet's red flag is at 1/5 of AD along the 8th line, so its coordinates are (8, 20).
- The distance between the flags is √[(8 − 2)² + (20 − 25)²] = √[36 + 25] = √61 m.
- The midpoint for Rashmi's blue flag is ((2 + 8)/2, (25 + 20)/2) = (5, 22.5).
why?
The midpoint of the join of (x₁, y₁) and (x₂, y₂) is ((x₁ + x₂)/2, (y₁ + y₂)/2): each coordinate is the average of the two ends.
Answer: The flags are √61 m apart, and Rashmi should post the blue flag at (5, 22.5).
Ex 7.2 Q4
In what ratio does (−1, 6) divide the join of (−3, 10) and (6, −8)?
- Let the point (−1, 6) divide the segment joining (−3, 10) and (6, −8) in the ratio k : 1.
- Using the section formula for the x-coordinate: (k × 6 + 1 × (−3)) / (k + 1) = −1.
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- Simplifying the numerator gives 6k − 3, so (6k − 3) / (k + 1) = −1.
why?
Simplifying (combining like terms, cancelling common factors) changes how the expression looks, not its value, so the next step is easier.
- Multiplying both sides by (k + 1) yields 6k − 3 = −(k + 1).
why?
Doing the same thing to both sides of an equation (adding, subtracting, multiplying or dividing by the same non-zero number) keeps the two sides equal, so the equation stays true while the unknown is left on its own.
- Expanding the right side gives 6k − 3 = −k − 1.
why?
Expanding multiplies every term in one bracket by every term in the other: (a + b)(c + d) = ac + ad + bc + bd.
- Adding k to both sides results in 7k − 3 = −1.
why?
Doing the same thing to both sides of an equation (adding, subtracting, multiplying or dividing by the same non-zero number) keeps the two sides equal, so the equation stays true while the unknown is left on its own.
- Adding 3 to both sides gives 7k = 2.
why?
Doing the same thing to both sides of an equation (adding, subtracting, multiplying or dividing by the same non-zero number) keeps the two sides equal, so the equation stays true while the unknown is left on its own.
- Dividing by 7 gives k = 2/7.
- Thus, the ratio is 2/7 : 1, which simplifies to 2 : 7.
why?
Simplifying (combining like terms, cancelling common factors) changes how the expression looks, not its value, so the next step is easier.
Answer: 2 : 7
Ex 7.2 Q5
In what ratio does the x-axis divide the join of A(1, −5) and B(−4, 5)? Find the point of division.
- Let the x-axis divide the line segment AB at point P in the ratio k : 1.
- Since P lies on the x-axis, its y-coordinate is 0.
- Using the section formula for the y-coordinate: 0 = (k(5) + 1(-5)) / (k + 1).
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- Solving the equation: 5k - 5 = 0, which gives k = 1.
- So, the ratio in which the x-axis divides AB is 1 : 1.
- Now, find the x-coordinate of P using the section formula: x = (1(-4) + 1(1)) / (1 + 1).
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- Calculating x: x = (-4 + 1) / 2 = -3/2.
- Thus, the point of division is (-3/2, 0).
Answer: The x-axis divides AB in the ratio 1 : 1 and the point of division is (-3/2, 0).
Ex 7.2 Q6
(1, 2), (4, y), (x, 6) and (3, 5) are the vertices of a parallelogram in order. Find x and y.
- Let the vertices of the parallelogram be A(1, 2), B(4, y), C(x, 6), and D(3, 5).
- In a parallelogram, the diagonals bisect each other, so the midpoint of diagonal AC is equal to the midpoint of diagonal BD.
- The midpoint of AC is ((1 + x)/2, (2 + 6)/2) = ((1 + x)/2, 4).
why?
The midpoint of the join of (x₁, y₁) and (x₂, y₂) is ((x₁ + x₂)/2, (y₁ + y₂)/2): each coordinate is the average of the two ends.
- The midpoint of BD is ((4 + 3)/2, (y + 5)/2) = (7/2, (y + 5)/2).
why?
The midpoint of the join of (x₁, y₁) and (x₂, y₂) is ((x₁ + x₂)/2, (y₁ + y₂)/2): each coordinate is the average of the two ends.
- Equating the x-coordinates of the midpoints: (1 + x)/2 = 7/2.
why?
The midpoint of the join of (x₁, y₁) and (x₂, y₂) is ((x₁ + x₂)/2, (y₁ + y₂)/2): each coordinate is the average of the two ends.
- Multiplying both sides by 2 gives 1 + x = 7.
why?
Doing the same thing to both sides of an equation (adding, subtracting, multiplying or dividing by the same non-zero number) keeps the two sides equal, so the equation stays true while the unknown is left on its own.
- Solving for x gives x = 6.
- Equating the y-coordinates of the midpoints: 4 = (y + 5)/2.
why?
The midpoint of the join of (x₁, y₁) and (x₂, y₂) is ((x₁ + x₂)/2, (y₁ + y₂)/2): each coordinate is the average of the two ends.
- Multiplying both sides by 2 gives 8 = y + 5.
why?
Doing the same thing to both sides of an equation (adding, subtracting, multiplying or dividing by the same non-zero number) keeps the two sides equal, so the equation stays true while the unknown is left on its own.
- Solving for y gives y = 3.
Answer: x = 6, y = 3
Ex 7.2 Q7
AB is a diameter of a circle with centre (2, −3) and B = (1, 4). Find A.
- The centre of the circle is the midpoint of its diameter AB.
- Let the coordinates of point A be (x, y).
- Using the midpoint formula, the x-coordinate of the centre is (x + 1) ÷ 2.
why?
The midpoint of the join of (x₁, y₁) and (x₂, y₂) is ((x₁ + x₂)/2, (y₁ + y₂)/2): each coordinate is the average of the two ends.
- Set (x + 1) ÷ 2 equal to the x-coordinate of the centre, which is 2.
- Solving x + 1 = 4 gives x = 3.
- Using the midpoint formula, the y-coordinate of the centre is (y + 4) ÷ 2.
why?
The midpoint of the join of (x₁, y₁) and (x₂, y₂) is ((x₁ + x₂)/2, (y₁ + y₂)/2): each coordinate is the average of the two ends.
- Set (y + 4) ÷ 2 equal to the y-coordinate of the centre, which is −3.
- Solving y + 4 = −6 gives y = −10.
Answer: A = (3, -10)
Ex 7.2 Q8
A = (−2, −2), B = (2, −4). Find P on segment AB with AP = (3/7)AB.
- The point P divides the segment AB in the ratio AP : PB = 3 : 4.
- Using the section formula, the x-coordinate of P is (4 × (−2) + 3 × 2) / (4 + 3).
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- Simplifying the x-coordinate gives (−8 + 6) / 7 = −2/7.
why?
Simplifying (combining like terms, cancelling common factors) changes how the expression looks, not its value, so the next step is easier.
- Using the section formula, the y-coordinate of P is (4 × (−2) + 3 × (−4)) / (4 + 3).
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- Simplifying the y-coordinate gives (−8 − 12) / 7 = −20/7.
why?
Simplifying (combining like terms, cancelling common factors) changes how the expression looks, not its value, so the next step is easier.
Answer: (-2/7, -20/7)
Ex 7.2 Q9
Find the points that divide the join of A(−2, 2) and B(2, 8) into four equal parts.
- The points dividing the segment AB into four equal parts are the trisection points of the first half and the second half, or simply points at 1/4, 2/4, and 3/4 of the way from A to B.
- Let P, Q, and R be the points dividing AB in the ratios 1:3, 1:1, and 3:1 respectively.
- Using the section formula for P dividing AB in ratio 1:3, x-coordinate is (1×2 + 3×(−2)) / (1+3) = (2 − 6) / 4 = −1.
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- The y-coordinate of P is (1×8 + 3×2) / (1+3) = (8 + 6) / 4 = 14 / 4 = 7/2.
- So, the first point P is (−1, 7/2).
- Using the section formula for Q dividing AB in ratio 1:1 (midpoint), x-coordinate is (2 + (−2)) / 2 = 0 / 2 = 0.
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- The y-coordinate of Q is (8 + 2) / 2 = 10 / 2 = 5.
- So, the second point Q is (0, 5).
- Using the section formula for R dividing AB in ratio 3:1, x-coordinate is (3×2 + 1×(−2)) / (3+1) = (6 − 2) / 4 = 4 / 4 = 1.
why?
The point dividing the join of (x₁, y₁) and (x₂, y₂) in the ratio m : n is ((mx₂ + nx₁)/(m + n), (my₂ + ny₁)/(m + n)) — a weighted average of the two end points.
- The y-coordinate of R is (3×8 + 1×2) / (3+1) = (24 + 2) / 4 = 26 / 4 = 13/2.
- So, the third point R is (1, 13/2).
Answer: The points are (-1, 7/2), (0, 5), and (1, 13/2).
Ex 7.2 Q10
Find the area of the rhombus with vertices (3, 0), (4, 5), (−1, 4) and (−2, −1) in order (area = half the product of the diagonals).
- Let the vertices of the rhombus be A(3, 0), B(4, 5), C(−1, 4), and D(−2, −1).
- The diagonals of the rhombus are AC and BD.
- Calculate the length of diagonal AC using the distance formula: AC = √[(−1 − 3)² + (4 − 0)²].
why?
The distance between (x₁, y₁) and (x₂, y₂) is √[(x₂ − x₁)² + (y₂ − y₁)²]: the two differences are the legs of a right triangle and the distance is its hypotenuse.
- AC = √[(−4)² + (4)²] = √[16 + 16] = √32.
- Calculate the length of diagonal BD using the distance formula: BD = √[(−2 − 4)² + (−1 − 5)²].
why?
The distance between (x₁, y₁) and (x₂, y₂) is √[(x₂ − x₁)² + (y₂ − y₁)²]: the two differences are the legs of a right triangle and the distance is its hypotenuse.
- BD = √[(−6)² + (−6)²] = √[36 + 36] = √72.
- The area of a rhombus is given by the formula: Area = ½ × (product of diagonals).
- Area = ½ × AC × BD = ½ × √32 × √72.
- Area = ½ × √(32 × 72) = ½ × √2304.
- Area = ½ × 48 = 24.
Answer: 24 square units
Other exercises in this chapter
- Exercise 7.1 — 10 questions
← Coordinate Geometry: notes, practice and all exercises
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