Question 889554
cos2A = sin3A
==> cos2A = cos(90 - 3A)
==> Either 2A = 90 - 3A or 2A = -(90 - 3A)
==> 5A = 90 or 2A  = -90 +3A
==> A  = 18 or A = 90.  These are the solutions from 0 degrees to 360 degrees.