A triangle has 3 sides, 1 hypotenuse ( the longest side, opposite to the right angle) and 2 legs ( a and b)
a = 9
b= 12
Since it is a right triangle, we can apply the Pythagorean theorem:
c^2 = a^2 + b^2
where c is the hypotenuse (x)
Replacing:
x = √( 9 ^2 + 12^2 )
x = 15
Answer: Hypotenuse = 15