Mark the correct alternative in the following:

If and then the value of A + B is

Mark the correct alternative in the following:

If A + B + C = π, then sec A (cos B cos C – sin B sin C) is equal to

Mark the correct alternative in the following:

tan 20^o + tan 40^o + √3 tan 20^o tan 40^o is equal to

Mark the correct alternative in the following:

If 3 sin x + 4 cos x = 5, then 4 sin x – 3 cos x =

Mark the correct alternative in the following:

If in a ∆ABC, tan A + tan B + tan C = 6, then cot A cot B cot C =