If cos(A-B) = √3/2 and secA = 2, 0°≤A ≤ 90°, 0°≤ B ≤ 90°, then what is the measure of B?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 30°
cos (A - B) = √3/2
secA = 2
0 ≤ A ≤ 900
secA = 2
cos A = 1/2 [sec A = 1/cos A]
cos A = cos 600 [cos 600 = 1/2]
A = 600 .....(1
cos (A - B) = √3/2
cos (A - B) = cos 300 [cos 300 = √3/2]
A - B = 300
600 - B = 300 [A = 600]
B = 600 - 300 = 300