I encountered this problem while practicing for a mathematics competition.
A cube has a diagonal length of 10. What is the surface area of the cube? No Calculators Allowed.
(Emphasis mine)
I'm not even sure where to start with this, so I scribbled down some numbers and solved for a square instead of a cube. Presumably, you can calculate the diagonal of a cube using the Pythagoras Theorem somehow, though I'm not sure how.
Best Answer
It is just the pythagorean theorem: