From each vertex, N-4 diagonals can be drawn, where N is the number of vertices. The total number of diagonals in a prism will be N(N-4)/2, where N is the number of vertices.

For N=10 (a pentagonal prism), the number of diagonals is (10)(6)/2 =

Half of them are space diagonals.

For N=10 (a pentagonal prism), the number of diagonals is (10)(6)/2 =

**30**.Half of them are space diagonals.