Did you know a Hexagon can be constructed using the angle pi/3 a lot of times? This is because a hexagon is made of 6 triangles with equal side length - the radius of the hexagon. The inner angles of these triangles is pi/3. Using this information and the trigonometric functions sin and cos can be used to draw such a picture.
non joke answer: the bee is compelled to build wax, wax takes a comparative large amount of effort and calories to produce, so they evolved to use a shape that requires the least effort and takes the most space. It could've been squares, but squares are harder to form and less compact, so it's likely they started with blobs/circles, and over millions of years, more closely, densely packed hives survived where others didn't until they ended up at the idea shape of a hexagon.
I know, and you're right. It's space efficiency and strength. Hexagon is much stronger than squares.