It's possible to demonstrate and prove mathematically that the angle sum of every triangle is 180 degrees. The techniques used are useful for solving all kinds of other geometry problems too.

Since there are 5 triangles, the sum of the angles inside the shape is \(5 \times 180 = 900^{\circ}\) b) The shape is a regular heptagon, so all the angles must be equal. The shape has 5 sides and ...