IdentityMediumQuestion 200052
Question
cos 2A in terms of tan A is:
- A(1−tan²A)/(1+tan²A)Correct
- B(1+tan²A)/(1−tan²A)
- C2 tan A/(1+tan²A)
- D2 tan A/(1−tan²A)
Correct answer
(1−tan²A)/(1+tan²A)
Explanation
cos 2A = (cos²A − sin²A)/(cos²A + sin²A) = (1−tan²A)/(1+tan²A) after dividing numerator and denominator by cos²A.