Question

In the figure above, what is the area of triangle QRS?

Answer 1

D) 20.

Explanation:

First find the value of x using Pythagoras theorem:

10^2 = x^2 + (2x)^2

5x^2 = 100

x^2 = 20

x = √20

= 2√5.

So the area of triangle

= 1/2 * base * height

= 1/2 * 2x * x

= x^2

= (2√5)^2

= 20.