Pythagorean theorem would be a^2 x b^2= c^2
What you will do is plug in whatever the side you have for your triangle into where a and b is. It really doesn't matter exactly as long as you know that on the longest side of your triangle will always be your c. Next you will square those numbers then add them together. After add them together you will take the square root of that number to where you'll knock it off of your c and you will get your answer.
HOPE THIS HELPS AND HAPPY VALENTINE'S DAY!