Then comparing two numbers MxM and M, MxM must be greater than M if M is not 1. It holds 1 is equal to -1. It holds 12 is equal to zero. The proposion is obtained by solving the equations. It holds 2 is equal to zero.
Every triangle is isosceles.
Let triangle ABC be an arbitrary triangle which was given. First, draw an auxiliary line from the vertex A that divides the angle BAC into two halves. Then these two triangles BGD and CGD become equivalent, that makes two line segments BG and CG have the same length. Then two triangles AGF and AGE become equivalent because the angle AGF is equal to the angle AGE and the edge AG is common to these triangles. Here, we got that the lenght of the segments AF and AE must be equal, and also FG and EG be equal.