Use the Pythagorean theorem for side lengths and trigonometric ratios for a specified acute angle. The opposite and adjacent sides depend on which angle you choose.
Key Rules
For a right triangle, leg² + leg² = hypotenuse².
Sine is opposite/hypotenuse; cosine is adjacent/hypotenuse; tangent is opposite/adjacent.
The hypotenuse is opposite the right angle and is the longest side.
Common Mistakes to Avoid
Using a leg as the hypotenuse.
Keeping “opposite” and “adjacent” labels when switching to the other acute angle.
SAT Strategy Tips
→Draw or label the reference angle before choosing a ratio.
→Check the calculator’s angle setting if an angle calculation is needed.
Example Question
A right triangle has legs of length 6 and 8. What is the sine of the angle opposite the 6-unit leg?
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