Polygons can be regular or irregular. If the angles are all equal and all the sides are equal length it is a regular polygon. To find the sum of interior angles in a polygon divide the polygon into ...

vi) (Motivate) If a side of a triangle is produced, the exterior angle so formed is equal to the sum of the two remote interior angles. 2. Triangles i) (Motivate) Two triangles are congruent if any ...

A nonagon has nine sides and a decagon has ten sides. To understand polygons, a good understanding of other angle rules, including triangles and quadrilaterals can be helpful. The word for the name of ...