Mathematics

If cos 60° = 1/2, which of the following angle has cosine of -1/2?

If cos 60° = 1/2, which of the following angle has cosine of -1/2?

  • A.
    30o
  • B.
    120o
  • C.
    150o
  • D.
    210o
  • E.
    300o
Correct Answer: Option B
Explanation

cos 60° = 1/2, cos(180° – 60°) = -1/2
cos120° = -1/2