Finding the Equation of Tangent line on cos wave

[slash123]

Finding the Equation of Tangent line on cos wave!

Find the equation of the normal line to y = 2cos ( 4x) at x = \pi / 3
I don't even know where to start with this question, i have searched the textbook and internet, help would be appreciated.

 

[Borek]

So tangent or normal?

Tangent should be quite easy - what do you know about value of derivative at a point?

What do you know about normal and tangent? Any specific angle between them?

 

[slash123]

its finding the normal sorry, should of said that instead,, what I've put in as the question is all the questions asks.

 

[Borek]

It doesn't change much - try to answer questions from my previous post.

 

[HallsofIvy]

Since this problem doesn't have anything to do with differential equations, I am moving it to "Calculus".

 

[adriank]

Find the slope of the tangent line. From that you can find the slope of the normal line. You also know a point that the line passes through.