<P> In 1882, the task was proven to be impossible, as a consequence of the Lindemann--Weierstrass theorem which proves that pi (π) is a transcendental number, rather than an algebraic irrational number; that is, it is not the root of any polynomial with rational coefficients . </P> <P> In non-Euclidean geometry, squares are more generally polygons with 4 equal sides and equal angles . </P> <P> In spherical geometry, a square is a polygon whose edges are great circle arcs of equal distance, which meet at equal angles . Unlike the square of plane geometry, the angles of such a square are larger than a right angle . Larger spherical squares have larger angles . </P> <P> In hyperbolic geometry, squares with right angles do not exist . Rather, squares in hyperbolic geometry have angles of less than right angles . Larger hyperbolic squares have smaller angles . </P>

Which type of square can be used to check only right angles