Geometry

Pythagorean theorem and right triangles

a² + b² = c² works on every right triangle.

Identify the right angle

The hypotenuse is the side OPPOSITE the right angle. The other two sides are the legs. Always plug the hypotenuse in for c, never for a or b.

Memorize three triples

3-4-5, 5-12-13, and 8-15-17 are right triangles. If you see two of those numbers, the third is automatic — no calculation needed. Doubles work too: 6-8-10, 9-12-15, etc.

Watch for embedded right triangles

A diagonal of a rectangle, the height of an equilateral triangle, the radius from the center to a chord — these all create right triangles. Look for them.

Tip: revisit this strategy after every 10 missed questions on this topic.