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