A hendecagon,
Yes it is. See link for more information
Decagon
ambot lang?
A decagon.
ninagon
it is called a unbalnced shpe
It really depends on the type of harp. Most are triangular shaped, but Celtic harps are more curved, almost like a mango shape.
A cone.
A pentagon
A 27 sided shape is called a Icosikaiheptagon.
A 27-sided polygon would be called an icosiheptagon.