Why does OpenGL use degrees instead of radians?

Question

The OpenGL designers were never afraid of mathematics, and knowledge of linear algebra is essential for all but the simplest OpenGL applications. I think it can safely be assume

Answer 1

I think it is because you should be able to get an exact rotation matrix for certain angles like 90 or 180 degrees. Like other people here has specified, if you use pi/2 instead of 90 degrees, rounding errors may lead to a transformation matrix that almost performs a rotation by 90 degrees.