NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 7: Coordinate Geometry - Exercise 7.2
Question 9

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.

Detailed Answer with Explanation:

Step 1: Recall what trisection means.

Trisection of a line segment means dividing it into 3 equal parts. So, two points divide the line segment in the ratio \(1:2\) and \(2:1\).

Step 2: Formula for internal division of a line.

If a point \(P(x, y)\) divides the line joining two points \((x_1, y_1)\) and \((x_2, y_2)\) in the ratio \(m:n\), then

\[ P(x, y) = \Bigg( \dfrac{m x_2 + n x_1}{m+n},\, \dfrac{m y_2 + n y_1}{m+n} \Bigg) \]

Step 3: Apply the formula for ratio \(1:2\).

Here, we take \(A(7, -2) = (x_1, y_1)\) and \(B(1, -5) = (x_2, y_2)\).

Ratio = \(1:2\). That means \(m = 1, n = 2\).

Step 4: Calculate the x-coordinate.

\[ x = \dfrac{1 \cdot 7 + 2 \cdot 1}{1+2} = \dfrac{7 + 2}{3} = \dfrac{9}{3} = 3 \]

Wait! This is not \(5\). Let’s try ratio \(2:1\) instead (because we need both trisection points).

Step 5: Calculate again for ratio \(2:1\).

Now \(m = 2, n = 1\).

\[ x = \dfrac{2 \cdot 7 + 1 \cdot 1}{2+1} = \dfrac{14 + 1}{3} = \dfrac{15}{3} = 5 \]

Step 6: Calculate the y-coordinate for ratio \(2:1\).

\[ y = \dfrac{2 \cdot (-2) + 1 \cdot (-5)}{2+1} = \dfrac{-4 - 5}{3} = \dfrac{-9}{3} = -3 \]

Step 7: Final Result.

So, the point is \((5, -3)\), which matches the given point \(P(5, -3)\).

Conclusion: Yes, the given point is one of the trisection points. Hence, the statement is True.

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 7: Coordinate Geometry – Exercise 7.2 | Detailed Answers