The sum of the angles in a triangle is 180°. To find the sum of the interior angles of a polygon, multiply the number of triangles in the polygon by 180°.

The Trisection of the Angle by Plane Geometry: Verified by Trigonometry with Concrete Examples. By Dr. J. Whiteford. Pp. 169.

Researchers have discovered how plants set the angles of their branches relative to gravity. While the other principle features governing the architecture of plants such as the control of the ...