Surface Areas and Volumes

Surface Areas and Volumes

TGM Original

Use perpendicular height \(h\) for volume. For a right circular cone, slant height \(l=\sqrt{r^2+h^2}\). Surface area counts only exposed surfaces.

SolidVolumeSurface area
Prism\(Bh\)\(2B+Ph\) for a right prism
Cylinder\(\pi r^2h\)\(2\pi r^2+2\pi rh\)
Right pyramid\(\dfrac13 Bh\)Base plus areas of triangular faces
Right circular cone\(\dfrac13\pi r^2h\)\(\pi r^2+\pi rl\)
Sphere\(\dfrac43\pi r^3\)\(4\pi r^2\)
Hemisphere\(\dfrac23\pi r^3\)Curved: \(2\pi r^2\); closed: \(3\pi r^2\)

Here \(B\) is base area and \(P\) is base perimeter. Split a composite solid into familiar pieces. Add or subtract volumes; do not count joined or hidden faces in the exposed area.

Example

A hemisphere of radius \(3\) is joined to a cylinder of radius \(3\) and height \(5\), with its lower circular base exposed.

\(V=\pi(3)^2(5)+\dfrac23\pi(3)^3=63\pi\)

\(A=2\pi(3)(5)+2\pi(3)^2+\pi(3)^2=57\pi\)

Area uses square units; volume uses cubic units. Convert all lengths to one unit before substitution.

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