A.4 Geometry and trigonometry

Circumference measures a boundary, area measures a surface and volume measures three-dimensional space. Select the formula that matches the shape and quantity being asked for.

Convert all lengths to one unit before squaring or cubing; show the formula and keep units as cm, cm² or cm³ as appropriate.

A sphere of radius r has surface area 4πr² and volume 4πr³/3; replacing r with diameter without halving it overestimates both.

A correct formula with mixed units can still produce a wrong answer, and surface area is not volume.