Distance

Cosmin Negruseri
08 octombrie 2013

Here's a neat problem I solved in 8th grade during the preparation for the high school entrance exam:

Let A1B1C1D1A2B2C2D2 be a cube with A1B1C1D1 being the bottom face and A2B2C2D2 the four corners of the top face. Given that A1A2 is of length 1 what's the distance between D2A1 and A2B1.