Image caption, STEP 3: Place the compass at the points where the arcs cross the circle and ... join the ends of the line to the dot – you now have a regular equilateral triangle.

Circle, triangle, and square. They’re simple, geometric, and eerily familiar. They look like something pulled straight out of a PlayStation controller or a childhood game of tic-tac-toe.

The radius of a circle is a line, which starts at the centre of the ... therefore this forms an isosceles triangle inside the circle. Also, note that since triangle AOB is isosceles, then ...