Question 159400: What is the formula to find out what the some of all of the interior angles in a non regular pentagon? Answer by vleith(2983) (Show Source):
You can put this solution on YOUR website! Not sure if I know a 'formula'. But here is what I would do. You have a figure with 5 sides on it. By adding two lines between three vertexes, you ought to be able to 'split' the pentagon into 3 triangles. Assuming you can do that, and knowing each triangle has 180 degrees in it, you get 3*180 = 540
Look here at a regular pentagon example. The idea is the same and the fact that it is non-regular shouldn't matter
http://www.coolmath.com/interior.htm
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