To go from Radians to Angles, all you need to do is divide by PI and multiply by 180.
You can use the Rad(A) function, or you can use the degree operator A° in any expression. If you're not using the Expression Editor but want to type the degree operator directly into the menu-expression-text-field, then use "". Thus, type in "A" and Grasshopper will replace that with the Degree symbol.