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Illustration used to prove "If the sides of any polygon are prolonged in succession one way, no two adjacent sides being prolonged through the same vertex, the sum of the exterior angles thus formed is four right angles."

Sum of Exterior Angles of a Polygon Proof

Illustration used to prove "If the sides of any polygon are prolonged in succession one way, no two…

Illustration used to prove "The sum of all the angles of any polygon is twice as many right angles as the polygon has sides, less four right angles."

Sum of Interior Angles of a Polygon Proof

Illustration used to prove "The sum of all the angles of any polygon is twice as many right angles as…