# Calculus(f(x)= tan(2x)

## Homework Statement

If f(x)= tan(2x), then f'(pi/6) =

## Homework Equations

deriv. of tan(pi/3)

## The Attempt at a Solution

How can I solve this? I am not supposed to use a calculator?? tan(pi/3) ...am I supposed to memorize this?

What is f'(x) ?
Hint: use the chain rule.

tan(pi/3) ' = sec^2(pi/3) is it??

And now how can you simplify that using the definition of sec?

Mark44
Mentor

## Homework Statement

If f(x)= tan(2x), then f'(pi/6) =

## Homework Equations

deriv. of tan(pi/3)
The derivative of tan(pi/3) is zero. tan(pi/3) is a constant, and the derivative of any constant is zero.

## The Attempt at a Solution

How can I solve this? I am not supposed to use a calculator?? tan(pi/3) ...am I supposed to memorize this?
Yes. There are a few angles whose trig functions you should have memorized - 0, pi/6, pi/4, pi/3, pi/2, as well as their supplements and combinations with pi/2, pi, and so on. You should also have memorized all of the six trig functions in terms of the sine or cosine.

And now how can you simplify that using the definition of sec?

Can you write sec x in terms of sine and/or cosine? You should have memorized the values of sin(pi/3) and cos(pi/3)