10
A decagon
A decagon.
A decagon is ten sided. The total of all the angles inside the corners of an n-sided polygon is (n-2)x180 degrees. So for 10 sides this is 8x180=1440 degrees. The polygon does not even have to have equal sides.
Its not a do-decagon its a dodecahedran!!
it depends on what you mean by a diagonal. If you take a diagonal to mean a line from one corner to the "opposite" corner, then a nonagon doesn't have any, and a decagon has five. The reason a nonagon doesn't have any, is that the corners aren't opposite each other.
It depends on whether or not the decagon is a perfect decagon or a complex decagon. However, a perfect decagon has no acute angles.
A decagon has ten vertices.
A decagon has 10 sides
A decagon has 10 sides
A decagon has 10 sides
There are 1440 degrees in a decagon.