Squaring the circle
Squaring the circle is a problem of geometry. The problem is to construct a square that has the same area as the unit circle, only by using a compass and straightedge construction method. Some people also call this problem the quadrature of the circle.
This is not about a circle with corners like a square. It is a problem like squaring a triangle. It is easy to construct a square with the same area as a triangle. Squaring the circle is related to the other ancient problems which have been proved impossible, squaring the cube and trisecting the angle.