GEO-08 · Geometry and Trigonometry

Special right triangles

Lines, angles, and triangles · Stage 3

01 · Key idea

A 45°–45°–90° triangle has side ratio 1:1:√2.

Useful rule45-45-90; 30-60-90 ratios

Build on: GEO-07

02 · Worked example

A 45°–45°–90° triangle has a leg of 5. Find the hypotenuse.

This teaching example is original and is not an official SAT question.

Reasoning

Multiply the leg by √2.

Answer

5√2

03 · Next step

Practice questions remain in English, as on the SAT.

GEO-08 · Special right triangles