Question

Peter is making an "X marks the spot" flag for a treasure hunt. The flag is made of a square white flag with sides of 121212 inches. He will make the "X" by stretching red ribbon diagonally from corner to corner.
How many inches of ribbon will Peter need to make the "X"?

Answer 1

The "X marks spot" on flag will be made along the diagonal of the flag. The shape of flag is square with each side 12 inches long. The diagonals of a square are equal in length. So the inches of ribbon needed to make the mark will be 2 times the length of a diagonal. 

The length of diagonal of square with side 12 inches will be:
$\sqrt{ 12^{2}+ 12^{2} }= \sqrt{288} =16.97$

The length of one diagonal is 16.97 inches. The length of 2 diagonals will be 33.94 inches or approximately 34 inches.

Therefore, 34 inches of ribbon will be needed to make the mark X on a square shaped flag having a side length of 12 inches.