Demonstrate that the interior angle sum of a triangle in...

Quick preparation

• demonstrate that the interior angle sum of a triangle in the plane is 180° and apply this to determine the interior angle sum of other shapes and the…
• using concrete materials to demonstrate that the sum of the interior angles of a triangle is 180°; for example, using paper triangles and tearing to…
• using decomposition and the angle sum of a triangle to generalise the interior angle sum of an n-sided polygon, as 180(n-2)\;=\;180n-360