There are several chickens and rabbits in a cage (with no other types of animals). there are 72 heads and 200 feet inside the cage. how many chickens and rabbits are in the cage? each animal has one head. so 72 heads tell us that rabbits + chickens = 72.

Use pythagorean’s theorem and find the missing side lengths of the two smaller triangles and add them together
13^2 - 12^2 = 5
15^2 - 12^2 = 9
5+9 = 14
14 is the length of each side of the square
14^2 + 14^2 = 19.8
19.8 is the diagonal length of the inside if the square