three parted circle: draw a line 3 cm long then mark the 0.5 cm points. draw a circle with the line touching the widest point. then draw the top half of a circle with a 0.5 cm radius on the left. draw the lower half of a circle with a 0.5 cm radius on the right side.
draw the upper half of a circle with a 1 cm radius on the left, and the lower half of a circle with a 1 cm radius on the right side.
to draw a circle with 4 parts, instead draw a 4 cm line and two more semi-circles with a radius of 1.5cm. to draw a circle with five parts, draw a 5 cm line and add two more semi-circles, with 2cm radii, and so on.
in a three part circle the red section is only a third of the total area. in a four section circle the red part is only a quarter of the area, and so on. prove it by drawing it