Iam doing the pythagorean theorum. the bottom of a 13 foot straight ladder is set into the ground 5 feet away from the wall. when the top of the ladder leaner against the wall, what was the distance above the ground it will reach

This is how you solve for the unknown side since 13 is the hypotensue and 5 is a leg.

5^2+b^2=13^2
25+b^2=169
b^2=144
b=12

You can also remember that any triangle with sides 5, 12, 13 is a special right triangle much like one with sides 3, 4, 5

Hope this helps