Foundation and Higher · volume of prisms

One formula works
for every prism.
Even a cylinder.

find the face
that repeats

first, what makes a —

Prism

the same shape all through

slice it anywhere: same face

example 1 of 2

Triangular prism

1. Find the cross-section: the face that
runs all the way through.

2. Its area: ½ × 6 × 4 = 12 cm².

✓ Volume = cross-section × length
= 12 × 10 = 120 cm³

example 2 of 2

1. A cylinder is a prism too. Its
cross-section is a circle.

2. Its area: π × 3² = 9π cm².

✓ Volume = πr² × height
= 9π × 10 = 90π cm³

one formula for all of them —

Prism

same cross-section all through

Volume

area of that face × length

Find the face that repeats —
that’s your cross-section.

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