A short video showing how to find right-angled triangles in other shapes to help solve geometry problems.

Use a pen to draw a dot where the arcs meet directly above the original horizontal line. Use a ruler and pen to join the ends of the line to the dot – you now have a regular equilateral triangle.

To represent this in two dimensions, again draw an equilateral triangle, followed by a circle centered around one of the triangle’s vertices, with a radius as long as each of the triangle’s legs.