Question

How do you solve these kind of problems ?
Is there a formula ?

Answer 1

In a right triangle, the hypotenuse is always bigger in length than the other two sides.

Pythagorean Theorem
\[A ^{2} + B ^{2} = C ^{2}\]

Lets look at the choices:
A. 5, 12, 13
\[5 ^{2} + 12 ^{2} = 13 ^{2}\]
25 + 144 = 169
169 = 169
So the answer is A.