JEE Mains Model Paper 14

Question : 84 of 90

Marks: +1, -0

If 2 sin θ . sec 3θ = tan 3θ - tan θ , then 2 [sin θ . sec 3θ + sin 3θ . sec 32θ + .. + sin 3n−1θ . sec 3nθ] =