In this case what we know is the length of the side of the polygons.
First thing you have to do is dividing drawing sheet into 5 parts:
1. PENTAGON KNOWING ITS SIDE. S=3 cm.
2. HEXAGON KNOWING ITS SIDE. S=3 cm.
3. HEPTAGON KNOWING ITS SIDE. S=2.5 cm.
4. OCTAGON KNOWING ITS SIDE. S=2.5 cm.
5. GENERAL METHOD FOR INSCRIBING POLYGONS IN CIRCLES.
This method will be used only when the polygon does not have a particular construction, nor can it be obtained as a multiple of another, since this procedure has inherent great imprecision.
It is used to draw polygons inscribed in a circle of any number of sides.
The greater the number of sides, the greater the imprecision.
We are going to use it to draw an inscribed decagon in a circle r=3.5 cm.
Complete drawing sheet: