`int(dx)/(1+cosx)`

Answer

N/a

Explanation

Let `I = int(dx)/(1+cosx)= int(dx)/(1+2cos^(2)'(x)/(2)-1)`
`= 1/2int(1)/(cos^(2)'x/2)dx = 1/2intsec^(2)'x/2dx`
`= 1/2.tan.'x/(2).2+C = tan'x/2+C[:' int sec^(2) x dx = tanx]`