Look at the compound figure below.
Think of it as a large cuboid with the dimensions a x b x d with a smaller cuboid of dimensions b x c x b cut out.
a = 10 cm
b = 4 cm
c = 2 cm
d = 6 cm
How would you calculate the volume?
We would need to find the volume of the large cuboid first and then subtract the volume of the small cut-out cuboid shape.
The large cuboid has lengths a, b and d, which is 10 x 4 x 6.
10 x 4 x 6 = 240
The smaller cut-out cuboid shape has lengths b, c and b again, which is 4 x 2 x 4
4 x 2 x 4 = 32
So the volume of the shape above is 240 - 32 = 208 cm3
Let's have a go at some questions now.