ok, this is what your professor means, it seems
graph the sine and cosine function. then, on the x-axis, locate the point , then, trace a vertical line to your graph, then a horizontal line from where it hits the graph to the y-axis. the value you get on the y-axis is (or should be, if you draw to scale reasonably well) the value of the function at the said x-value
the question is how do i trace it to locate -31 (radius)/6, lol sry for previous questions, i understand that radius/6 is a 30 degree and that each radius has 6 slices in it. and one whole pie is 12. so can u clearify what my prof has said or try to explain it in a different way.