Answer:
Pythagoros Therom
Step-by-step explanation:
The pythagoros therom will help you find any side of a triangle as long as you already know 2 of the sides the equation is a^2+b^2=c^2 and c is the hypotenuse(the longest leg) and a and b are the other two legs. You might wanna learn this thouroghly but it is very easy to learn trust me.