Triangles with integral sides and circumradius.
A general formula giving such triangles was stated by Gauss, we propose to find a general formula giving prime solutions—that is, a formula giving integral sides and circumradius, a, b, c, R, which have highest common factor unity
If α β γ are the angles of an integral triangle, then sin α, sin β, sin δ and cos α, cos β, cos γ are rational.