Interior Angle And Exterior Angle Formula. The sum of the interior angles of a triangle is always 180. Interior angles of a Regular Polygon 180n 360 n.
The angle between two adjacent sides inside the polygon is known as the Interior angle. To find the exterior angle we simply need to take 135 away from 180. The sum of all the internal angles of a simple polygon is 180 n 2 where n is the number of sides.
Let us see the proof of this statement.
The sides of the angle lie on the intersecting lines. Starting with a triangle for which the angle sum is 180 then replacing one side with two sides connected at another vertex and so on. For our equilateral triangle the exterior angle of any vertex is 120. N Number of sides of polygon5.