Answer:
x = 15 cm
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 = 9² + 12² = 81 + 144 = 225 ( take square root of both sides )
x = [tex]\sqrt{225}[/tex] = 15
