Area of a polygon can be found by dividing the polygon into different triangles and finding the sum of areas of the individual triangles.
Examine the table. (Each figure is divided into triangles and the sum of the angles deduced from that.)
Figure
Side
3
4
5
6
Angle sum
180°
2 × 180°
= (4 − 2) × 180°
3 × 180°
= (5 − 2) × 180°
4 × 180°
= (6 − 2) × 180°
What can you say about the angle sum of a convex polygon with number of sides?
(a) 7
(b) 8
(c) 10
(d) n
Area of a quadrilateral can be found by splitting it into triangles.
The lines of symmetry of a regular polygon with n sides divide the polygon into __ triangles.