Constructing frame in octagon shape. What is the calculation that would be used to determine the mitre angle of each meeting piece of lumber. I know that an octagon has 1080 degrees so somone show me the math to get the mitre. Also explain how any mitre can be determined for any polygon shape such as hexagon , pentagon etc.

I would like to apply a more natural (lighter) finish to a dresser and chest of drawers that was stained "avocado green" and sprayed with black lacquer along all of the outermost corners. I am concerned that after applying the stripper, a dark discoloration will remain where the black lacquer was sprayed on the heaviest. Would the stain, which I imagine was laid down first, sufficiently have protected the veneer from absorbing the black lacquer? Another question: Because this is veneer, I am wary of using bleach or water based lightening solutions to lift out any remaining lacquer color--are there any other products that could do this safely on veneer? (I am hesitant to sand very hard on veneer). Any suggestions? : The set was manufactured in 1959.