The expression to be integrated is given below as,
I= ∫ tanx sinxcosx dx
Simplify the above integral,
I= ∫ tanx ×cosx sinxcosx×cosx dx = ∫ tanx sinx cosx × cos 2 x dx = ∫ tanx tanx cos 2 x dx = ∫ sec 2 x tanx dx
Let tanx=t
Differentiate with respect to t.
sec 2 xdx=dt
By substituting the value, we get
I= ∫ dt t = ∫ t −1/2 dt =[ t −1 2 +1 −1 2 +1 ] =2 t +C
On substituting tanx for t, we get
I=2 tanx +C