If sin(3A – 20°) = cos(20° – 3B), then the value of A – B is:

Correct option is A

Given:

sin(3A - 20°) = cos(20° - 3B)

Concept Used:

sin(x) = cos(90° - x)

Solution:

cos(90° - (3A - 20°)) = cos(20° - 3B)

cos(90° - 3A + 20°) = cos(20° - 3B)

cos(110° - 3A) = cos(20° - 3B)

110° - 3A = 20° - 3B

110° - 20° = 3A - 3B

90° = 3(A - B)

A - B = 30°