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.
| Solid | Volume | Surface 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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