# Sum of Exterior Angles of a Polygon Proof

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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.”

### Keywords

geometry, interior, proof, angle, angles, exterior, sum, theorem, polygonal angles, angles of a polygon### Galleries

Geometric Theorems and Proofs### Source

C.A. Hart, Daniel D. Feldman *Plane and Solid Geometry* (New York, NY: American Book Company, 1911)

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