I know I can simply use the calculator to find what the angle of a triangle would be, but I want to know how to find it using the standard triangles or the 30/60/90 triangles. Whatever you wish to call them.

I have the equation z=2+5i
So the modulus of the equation is sqrt 29.

What maths do I need to do in order to relate it to the standard triangles?

I've tried multiplying the hypotenuse of 2 by sqrt 29/2 but that just seems to cause havoc.