NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 6: Triangles - Exercise 6.4
Question 18

Question. 18

Prove that the area of the equilateral triangle on the hypotenuse of a right triangle equals the sum of the areas of the equilateral triangles on the other two sides.

Answer:

Proved.

Detailed Answer with Explanation:

Step 1: Recall the formula for the area of an equilateral triangle with side length \(x\).

Area = \(\dfrac{\sqrt{3}}{4}x^2\).

Step 2: In a right triangle, let the sides be:

  • Base = \(a\)
  • Height = \(b\)
  • Hypotenuse = \(c\)

Step 3: Draw equilateral triangles on each side \(a\), \(b\), and \(c\). Their areas will be:

  • On side \(a\): \(A_a = \dfrac{\sqrt{3}}{4}a^2\)
  • On side \(b\): \(A_b = \dfrac{\sqrt{3}}{4}b^2\)
  • On side \(c\): \(A_c = \dfrac{\sqrt{3}}{4}c^2\)

Step 4: From the Pythagoras theorem, we know that for a right triangle:

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

Step 5: Substitute this value of \(c^2\) into the area on side \(c\):

\(A_c = \dfrac{\sqrt{3}}{4}c^2 = \dfrac{\sqrt{3}}{4}(a^2 + b^2)\).

Step 6: Split the terms:

\(A_c = \dfrac{\sqrt{3}}{4}a^2 + \dfrac{\sqrt{3}}{4}b^2 = A_a + A_b\).

Final Result: The area of the equilateral triangle on the hypotenuse is equal to the sum of the areas of the equilateral triangles on the other two sides.

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 6: Triangles – Exercise 6.4 | Detailed Answers