A prism is a three-dimensional figure made of two equivalent parallel faces and rectangular faces that connect them. To find the volume of a prism, find the area of one of the parallel faces, and multiply by the perpendicular distance between them. You might need scratch paper and a calculator.
- Measure the dimensions of the base
Measure the edges of one of the parallel faces. This face is often referred to as a base. If the face is a right triangle, you only need to measure the perpendicular edges that intersect at a right angle.
- Find the area of the base
The area of most polygon bases can be found by multiplying some coefficient of length times height. For triangles, the area is one half of the length times the height (A = l*h/2). The perpendicular sides you measured are the length and height of a right triangle. Multiply them together, and divide the product by 2 to find the area. For example: if the right triangle face has one side that's 2cm long and another that's 3cm long, then the area is (2cm * 3cm)/2 = 3(cm^2).
- Calculate the volume
Multiply the area of the base by the distance between the bases. Measure that distance along the edge of a rectangle. For example, if the rectangle is 4cm long, the volume is 4cm*3(cm^2) or 12(cm^3).