Math Section · Study Guide

Geometry & Tape Measure

We teach perimeter, area, circumference, and tape-measure reading to 1/16 inch: all by hand, no calculator. Locals vary. Check your local's test format. Learn the shapes, then the ruler, then lock everything in with worked examples.

Rectangles

A rectangle has four right angles. Opposite sides are equal. Hover the labels below to highlight each dimension.

Perimeter = 2L + 2W = 2(12) + 2(8) = 40 in

Area = L × W = 12 × 8 = 96 in²

Triangles

For area, you need the base and the perpendicular height, the straight-line distance from the base to the opposite vertex. The dashed line shows the height.

Area = ½ × b × h = ½ × 14 × 10 = 70 in²

Circles

The radius goes from the center to the edge. The diameter is twice the radius. On the test, use π = 3.14 unless told otherwise.

Circumference = 2πr = 2 × 3.14 × 7 = 43.96 in

Area = πr² = 3.14 × 7² = 153.86 in²