Heptagons have seven sides.
You may be thinking of a heptagon. It has seven sides and seven angles.
An heptagon has 7 interior angles that add up to 900 degrees
A 11 sided shape is called a hendecagon.
The word is heptagon. A heptagon has 7 sides and 7 corners. If you join corners by straight lines from one corner to another corner you will find 5 triangles, but if you join all corners to a point in the centre you will find 7 triangles. The Heptathlon in athletics is a contest in which the participants must compete in 7 different athletic forms of athletics.