What is the derivative of y=sin(tan2x)?

1 Answer
Jan 5, 2016

dydx=2cos(tan2x)sec2(2x)

Explanation:

We need to apply the chain rule twice.

Recall that the chain rule states, if we have some function f(g(x)), the derivative of f with respect to x is equal to the derivative of f with respect to g, multiplied by the derivative of g with respect to x.

So in this case, the derivative dydx will equal the derivative of sin(tan2x) with respect to tan2x (basically, treat tan2x as a whole variable) times the derivative of tan2x with respect to x.

Derivative of sin is just cos:

dydx=cos(tan2x)ddx[tan2x]

Derivative of tan is sec2. However, we need to apply the chain rule again, meaning this time we will just pull the derivative of 2x out. (which is just 2)

dydx=cos(tan2x)sec2(2x)2