So, what's with the biscuits? Oh a triangulator machine! Very cool! Right, there are four different types of triangle. First, here's an isosceles triangle, it has two equal length sides and two ...

You'll be using Sketch 1 of this file which has three different types of triangles - scalene, isosceles, equilateral. Each triangle type has a different colour (pink for scalene, red for equilateral, ...

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.