The Pythagorean Theorem is: [tex] \alpha x^{2} +b x^{2} =c x^{2} [/tex]
So, for your problem, the hypotenuse is 13 and another side length is 5.
It doesn't matter if you put 5 in the equation as a or b.
The equation would be: [tex]5 x^{2} +b x^{2} =13 x^{2} [/tex]
To solve you would do 5*5=25 and 13*13= 169.
You would end up with: [tex]25 +b^{2}= 169 [/tex]
Subtract 25 from 169 to get 144. In order to get b by itself, you must square root both sides. The other side length is 12.
Then multiply 12 by 5 to get 60
Then divide 60 by 2 to get 30.
THE ANSWER IS 30.