A polygon is a many sided 2-dimensional figure, and thus could never be "solid"
Alternatively, it could be "one face that is a polygon". In that case the solid could be like a pyramid that morphs into a cone or a part-sphere. The base would be the one polygon, the other face would not.
a pyramid
Pyramid
a pyramid
Such a figure is a pyramid.
A polygonal pyramid.
a face.
It is called a face.
A pyramid is a solid figure with one face that is a polygon and three or more faces that are triangles with a common vertex. Yeah, pg. 114 in the math workbook is a little hard, and the guy who answered this before me thought it was funny to improve the answer by saying the answer was 45. That's just not mature. I don't get it. Anyway, I hope you finish your homework at this rate.
a polygonal prism or a polygond
cone
The answer is a cone
The sphere.