Posted by Kay on Friday, February 17, 2012 at 12:21am.
You know that a pentagon has 5 sides and 5 angles. So, if you already have one angle you only have to solve for four more, which happen to be equal. So, first determine the total degrees sum of the interior angles in a pentagon by using the formula: 180(n-2) where n is the number of sides in the polygon. So, the sum of interior angles in a pentagon is 540. And now that you have one of them, you know the sum of the remaining 4 is 540-20=520 degrees. And the problem also tells you that these last four angles are equal and obtuse! You are halfway done: just divided the remaining degrees, 520/4 and you get 130 degrees. Now check, is this obtuse? Yes, it is greater than 90 degrees but less than 180! Hope this helps!
140
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