Question

What is the value of r in the following diagram.
9
6

Answer 1

r = 3.75

Explanation:

Using Pythagoras' identity in the right triangle ABC

AC² = BC² + AB²

(r + 6)² = r² + 9²

r² + 12r + 36 = r² + 81 ( subtract r² from both sides )

12r + 36 = 81 ( subtract 36 from both sides )

12r = 45 ( divide both sides by 12 )

r = 3.75