Figure 3.3

Figure 3.3 shows an octagon. Five diagonals can be drawn from A. This gives rise to six triangles.

Since the sum of all internal angles of a triangle is 180⁰, the sum all the internal angles of this polygon is 6 ´ 180⁰ = 1080⁰.

This can be generalized as :

For any n sided polygon the sum of its internal angles is
( n - 2 ) ´ 180⁰.

Index

3. 1 Definition
3. 2 Terminology
3. 3 Sum Of Interior Angles Of A Polygon
3. 4 Sum Of Exterior Angles Of A Polygon
3. 5 Trapezoids
3. 6 Parallelogram
3. 7 Square, Rectangle And Rhombus