Answer:
x = 20
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 = 12² + 16² = 144 + 256 = 400 ( take the square root of both sides )
x = [tex]\sqrt{400}[/tex] = 20
