1 . ∫dx1+3cos2x=কত? 

• A. $\frac{1}{2}{\tan }^{-1}\left(\frac{\tan x}{2}\right)+c$
• B. $\frac{1}{3}{\tan }^{-1}\left(\frac{\tan x}{2}\right)+c$
• C. $2{\tan }^{-1}\left(\frac{\tan x}{2}\right)+c$
• D. ${\tan }^{-1}\left(ex\right)+c$

Answer: Option A

Explanation: