Answer:
Explanation:
The specifications of a decagonal pyramid would be the following 
It has one face that is a decagon.
35 diagonals in the base. 
 
10 isosceles triangles as faces above the base 
 
11 vertices - 10 in the base and 1 at the top 
 
20 edges - 10 in the base and 10 above the base 
 
This can all be seen in the picture of the decagonal pyramid below. The only decagonal face is on the base of the pyramid as the top is a vertice where all of the triangles meet.