Question

Find the perimeter of a regular dodecagon whose vertices are twelve equally spaced points on the unit circle.

Answer 1

The vertex angle of any triangle of the dodecagon formed by radii and a side is 360/12=30º.
The half-length of the base of the triangle is sin15=0.2588 approx.
Since there are 12 sides there are 24 half-sides in the perimeter=6.2117.