How to answer it
- Label the sides relative to the angle in the question.
- Find any missing side with a² + b² = c².
- Write the ratio the question asks for.
Worked example
An original question in the SAT format, already answered.
SAT MathWorked example
In right triangle ABC, angle C is the right angle, AC = 5 and BC = 12.
What is the value of sin A?
- A5/12
- B5/13
- C12/13
- D13/12
Answer: C. AB = √(5² + 12²) = 13. The side opposite angle A is BC = 12, so sin A = 12/13. Choice B is cos A.
The most common trap
Labeling sides from the wrong angle. Opposite and adjacent depend on which angle you’re asked about.
Practice it
Hourly Prep’s daily sets mix right triangles and trigonometry with the rest of SAT Math, and send more of it your way when it’s a weak spot. See how the SAT prep plan works, or browse the other SAT skill guides.