Mark the 90° right angles in the bottom left and top right corners. You can split a rectangle into 2 right-angled triangles. Image caption, STEP 2: Use the compass to draw a circle. Put a dot ...

Showing that a parallelogram has the same area as a rectangle: Split the parallelogram into a right-angled triangle and a trapezium. Move the triangle to the other end of the shape, making a ...