Drawing a Pentagon with a Compass in Mechanical engineering Drawing

• Draw a circle that is to enclose the pentagon.

• Draw two perpendicular diameters. 

To do this:
1)   Draw an arbitrary chord.

2)   Divide the chord into halves, and construct a perpendicular.

3)   Divide the perpendicular into halves, and construct another perpendicular.

• Divide one radius into halves, and mark the midpoint (B).

• Using the distance from the midpoint (B) to the end of an adjacent radius (A), swing an arc through the opposite radius (C).

• Using the distance from the end of the adjacent radius (A) to the intersection of the arc and the opposite radius (C), swing an arc around the end of the adjacent radius to the edges of the circle (D and D').

• Using that same distance, repeat around the circle to mark off two more points (E and E').

• Connect the dots!