Answer:
x = 12
Step-by-step explanation:
Using Pythagoras' identity in the right triangle.
The square on the hypotenuse is equal to the sum of the squares on the other 2 sides, that is
x² + 81 = 15²
x² + 81 = 225 ( subtract 81 from both sides )
x² = 144 ( take the square root of both sides )
x = [tex]\sqrt{144}[/tex] = 12
