Answer: 40 cubic cm
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Step-by-step explanation:
The triangular face has area of base*height/2 = 4*10/2 = 40/2 = 20 square cm.
Multiply this prism base area by the depth of the prism to get 20*2 = 40 cubic cm.
It might help to place the triangular prism so the triangular face is along the ground, so you can think of that face as the floor of this triangular room. The volume of this room is equal to the floor area times the height of the room.
volume of the room = (floor area)*(height of the room)
volume of the prism = (base area)*(height of the prism)
For any prism, the base faces are always parallel and congruent to each other.