Volume of Prisms

You will normally be asked to find the volume of prisms on the calculator paper of your GCSE exam.  To be able to answer these questions you must learn the formulae for working out the area of basic 2D shapes, specifically rectangles, triangle, circles and trapeziums.

Example Question
a)  Find the volume of the shape below.

To find the volume of any prism we first to find the area of the cross section of the prism.  The cross section in this case is a trapezium.

First add the parallel sides: 14 + 8 = 22
Now multiply by the perpendicular height: 22 x 4 = 88
Finally divide your answer by two: 88 2 = 44 cm2.

Once we know the area of the cross section we multiply by the length of the prism to find the volume.

So 44 x 10 = 440 cm3.

Test Yourself!
Find the volume of the cylinder below.
Give your answer to the nearest whole number.

x = m3

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