Answer:
5
Step-by-step explanation:
Since this is a right triangle, we can use the Pythagorean theorem
a^2 + b^2 =c^2 where a and b are the legs and c is the hypotenuse
x^2 + 12^2 = 13^2
x^2 +144 =169
Subtract 144 from each side
x^2 +144-144 =169-144
x^2 = 25
Take the square root of each side
sqrt(x^2) = sqrt(25)
x=5
