How to build a pentagon with a caliper
Correct pentagon - a polygon in which all five sides and five angles are equal. Around it is easy to describe a circle. Construct a pentagon, and it will help this circle.
Instruction how to construct a pentagon with a caliper
The first step is to build a compass circle. Circle center let coincides with the point O. Spend a symmetry axis perpendicular to each other. At the intersection of one of the axes of the circle put a point V. This point will be the apex of the pentagon future. At the point of intersection of the other axis of the circle, place a point D.
On the segment OD find the middle and mark it point A. Then you have to build a compass circle centered at this point. In addition, it must pass through the point V, then have a radius CV. The point of intersection of the axis of symmetry and a circle mark of B.
After that, with the help of a compass draw a circle of the same radius, putting the needle in point V. The intersection of this circle with the original mark as the point F. This point will be the second vertex of a regular pentagon future.
Now you need to spend the same circle through the point E, but with center F. Crossing just drawn a circle with the original mark as the point G. This point also will become one of the vertices of the pentagon. Similarly, the need to build another circle. Its center of G. The intersection point it to the original circle so be H. This is the last vertex of a regular polygon.
You should now have five points. It remains simply to connect on line. As a result of these operations, you get a circle inscribed in a regular pentagon.