Proof that an N-gon is 180 Degrees

To prove that an n-gon is 180°, just divide the shape into triangles by drawing diagonals, then multiply 180° by the total number of triangles. For example, a quadrilateral can be split into two triangles by drawing a diagonal from one corner to the opposite corner. 180°x2=360°. Note that the number of triangles is always 2 less than the number of sides in the n-gon. For example, a pentagon will have three triangles and an octagon will have 6.


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Last updated: 02/19/2018
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