Geometry and TrigonometryVery hardCosine of the other acute angle
Geometry and Trigonometry practice question
In a right triangle, sin A = 5/13, where A is one of the acute angles. What is the cosine of the other acute angle?
Answer: 5/13
The two acute angles are complementary, so cos B = sin A = 5/13.
Common wrong answers
- If you answered 12/13
- 12/13 is cos A, not cos B.
- If you answered 5/12
- 5/12 is tan A.
- If you answered 13/5
- 13/5 inverts sin A.
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