All lessons › Unit 6 · Geometry and trigonometry

Right triangles

Right triangles show up a lot in SAT geometry. You need the Pythagorean theorem and two special triangles whose sides always have the same ratio. They also hide inside many other shapes.

This lesson starts with the Pythagorean theorem and shows a picture of why it works. Then it covers 45-45-90 and 30-60-90 triangles, which save a lot of calculating. Practice questions mix the Pythagorean theorem with the special triangles. We build from a simple picture of the triangle, and every answer is explained in plain words, step by step. The special triangles save time on test day.

In this lesson

• Pythagorean theorem
• Special right triangles