Question

The value of $\int \left(\cos x\tan x\right)dx$ is
(where $C$ is constant of integration)

• A. $-\sin x+C$
• B. $-\cos x+C$
• C. $-\cot x+C$
• D. $\sin x+C$

Answer 1

The correct option is B $-\cos x+C$

Let $I=\int \left(\cos x\tan x\right)dx$
$\Rightarrow I=\int \cos x\frac{\sin x}{\cos x}dx$
$=\int \sin xdx$
$=-\cos x+C$