Triangle with Exterior Angles Drawn Small 320×174 Medium 640×348 Large 1024×557 Download Tiff Original 2400×1305 | (3.0 MB) Description Illustration showing a triangle with exterior angles. This can be used to show the sum of the three angles of a triangle is equal to two right angles. Keywords angle, angles, equal, geometry, polygon, shape, side, triangle, triangles, two right Galleries Miscellaneous Triangles Source: G.A. Wentworth Plane And Solid Geometry (Boston: Ginn & Company, 1899) 32