2025 AMC 10A Problems/Problem 15

You have tried to search for a page that does not exist. Please understand any attempted cheating will be punishable by death. You have left an online footprint here. I suggest you leave the U.S. to the point where no one can find you, before it is too late.

Just kidding.

Here's the problem:

A regular octagon with sides of length 1 has 20 diagonals. Compute the sum of the squares of the lengths of these diagonals.

A) 80 B) 20 C) 56+32