Problems

Fred and George had two square cakes. Each twin made two straight cuts on his cake from edge to edge. However, one ended up with three pieces, and the other with four. How could this be?

Cut a square into three pieces, from which you can construct a triangle with three acute angles and three different sides.

Kai has a piece of ice in the shape of a “corner” (see the figure). The Snow Queen demanded that Kai cut it into four equal parts. How can he do this?

Is it possible to bake a cake that can be divided by one straight cut into 4 pieces?