If you have a right triangle and know 2 sides how do you find the other side?

The other side is 5. There is something in math called a pythagorean triple, which is what this right triangle is. You could learn some common pythagorean triples or you can learn the pythagorean theorem which always works for right triangles. That theorem is a^2 +b^2 = c^2 where a and be are the legs of the right triangle and c is the hypotenuse. I hope I spelled that right. So here your legs are 4 and 3. You have to do 4^2 +3^2 = 25. 25=c^2 so c =sqrt25 which equals 5. So the other side that completes the triangle is 5.