SAT Math Multiple Choice Question 651: Answer and Explanation
6. In triangle ABC, angle C has a measure of 90°. If sin A 5 0.6, what is the value of cos B?
- A. 0.3
- B. 0.4
- C. 0.6
- D. 0.8
Correct Answer: C
Advanced Mathematics (rational equations)
It always helps to draw a diagram for geometry and trigonometry problems. For this problem, we also have to remember the basic definitions of the trigonometric functions discussed in Chapter 10, Lesson 9: SOH CAH TOA.
Since sin A = 0.6, this means a/c = 0.6. Notice that cos B is also a/c, so it must also equal 0.6. This is an example of the cofunction identity we discussed in Chapter 10, Lesson 10.