This example demonstrates how to construct a pentagon using a straight edge and ruler.

- Start by drawing a circle whose size is proportional to the size of the pentagon you want to draw. Place a point at the center of the cicle draw a vertical line for the diameter of the circle.
- Draw a perpendicular line leftwards from the center of the circle. Draw a point where the line intersects with the circle.
- Bisect this line segment formed between the new point and the center of the circle.
- Draw a circle at this new point with a diameter equal to the radius of the starting circle. Then draw a line from the bottom-most point through of the center of the circle. Draw points at the two places the line intersects with the circle.
- Draw another circle and draw the points of intersection.
- Draw another circle and draw the points of intersection.
Connect the five points along the perimeter to form the pentagon.

We have finished constructing the pentagon.

How to construct a perpendicular line given a straight line.

This exampls shows how to bisect a line with compass and straight edge.