Thread: Simplifying

I need to evaluate the derivative of the function f(t)=t/cos(t) at the point (pi/3, 2pi/3). I know that I have to find the derivative of the function and then plug pi/3 into the derivative. I did that I just don't know how to simplify my answer.

I found the derivative to be f'(x)=(sec t)(t tan t + 1)
Please help

Originally Posted by rawkstar

I need to evaluate the derivative of the function f(t)=t/cos(t) at the point (pi/3, 2pi/3). I know that I have to find the derivative of the function and then plug pi/3 into the derivative. I did that I just don't know how to simplify my answer.

I found the derivative to be f'(x)=(sec t)(t tan t + 1)
Please help

Oh dear: some messy-looking way to put the derivative. Won't it be easier to visualize writing ?

Anyway, as , just plug in and evaluate.

Tonio

Hello rawkstar

Originally Posted by rawkstar

I need to evaluate the derivative of the function f(t)=t/cos(t) at the point (pi/3, 2pi/3). I know that I have to find the derivative of the function and then plug pi/3 into the derivative. I did that I just don't know how to simplify my answer.

I found the derivative to be f'(x)=(sec t)(t tan t + 1)
Please help

Using the quotient rule:

, which agrees with your answer



, which won't simplify any more unless you don't mind an irrational denominator, in which case you could write is as

Grandad