Right triangles and trigonometry

About this lesson

Right triangles and trigonometry on the SAT: the Pythagorean theorem and common triples, 45-45-90 and 30-60-90 triangles, sine, cosine and tangent, the identity sin x = cos(90° − x), trig ratios in similar triangles, and converting degrees to radians.

On the Digital SAT, right triangles and trigonometry are their own skill in the Geometry and Trigonometry domain. A question may ask for a missing side with the Pythagorean theorem, the sine or cosine of an angle from side lengths, an angle when the sine of one angle equals the cosine of another, a side of a 30-60-90 triangle, or a conversion between degrees and radians.

These points are usually lost to labeling rather than to forgotten formulas: the adjacent side used as the opposite one, the x√3 side placed across from the wrong angle, or a calculator left in radian mode on a degree question. This lesson shows how to label sides from the angle being asked about, how to spot familiar triples to save time, and how to build a triangle quickly from a given ratio. It ends with 6 self-graded practice questions, each with a full explanation.