SOLUTION: My question is the sum of seven of the angles of a decagon is 1170.the other three angles are all equal to each other. Calculate the sizes of the other three angles

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Question 1165063: My question is the sum of seven of the angles of a decagon is 1170.the other three angles are all equal to each other. Calculate the sizes of the other three angles

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
The sum of all the angles of an n-sided polygon is (n-2)(180°).
A decagon has 10 sides, so

the sum of all the angles of a decagon is (10-2)(180°) = (8)(180°) = 1440°.
the sum of seven of the angles of a decagon is 1170°.

So the remaining three angles have sum 1440°-1170° = 270°

Since they are equal, they are 270°/3 or 90° each.

Edwin