Chapter 3: Derivatives - Section 3.5 - Derivatives of Trigonometric Functions - Exercises 3.5 - Page 141: 7

The Derivative is: $y'=\sin x\sec^2 x+\sin x$

$f(x)=\sin x\tan x$ Using Product Rule to find the Derivative: $y'=h'(x)\cdot g(x)+h(x)\cdot g'(x)$ $y'=(\cos x)(\tan x)+(\sin x)(\sec^2 x)$ $y'=\cos x \frac{\sin x}{\cos x}+\sin x\sec^2 x$ $y'=\sin x\sec^2 x+\sin x$