A pentadecagon has how many sides?
Pentadecagon Pentadecagon In geometry, a pentadecagon or pentakaidecagon or 15-gon is a fifteen-sided polygon. A "regular pentadecagon" is represented by Schläfli symbol {15}. A regular pentadecagon has interior angles of 156°, and with a side length "a", has an area given by <br>A regular triangle, decagon, and pentadecagon can completely fill a plane vertex. As 15 = 3 × 5, a regular pentadecagon is constructible using compass and straightedge: The following constructions of regular pentadecagons with given circumcircle are similar to the illustration of the proposition XVI in Book IV of Euclid's "Elements". Comparison the construction according Euclid in this image:
Pentadecagon but connected by skipping every second, fourth, or seventh vertex respectively. There are also three regular star figures: {15/3}, {15/5}, {15/6}, the first being a compound of three pentagons, the second a compound of five equilateral triangles, and the third a compound of three pentagrams. Deeper truncations of the regular pentadecagon and pentadecagrams can produce isogonal (vertex-transitive) intermediate star polygon forms with equal spaced vertices and two edge lengths. The regular pentadecagon is the Petrie polygon for some higher-dimensional polytopes, projected in a skew orthogonal projection: It is also the Petrie polygon for the great 120-cell and grand stellated 120-cell.