# Finding the Equation of Tangent line on cos wave

1. Aug 31, 2010

### 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 dont even know where to start with this question, i have searched the text book and internet, help would be appreciated.

2. Aug 31, 2010

### Staff: Mentor

Re: Finding the Equation of Tangent line on cos wave!!!

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?

3. Aug 31, 2010

### slash123

Re: Finding the Equation of Tangent line on cos wave!!!

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

4. Aug 31, 2010

### Staff: Mentor

Re: Finding the Equation of Tangent line on cos wave!!!

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

Last edited by a moderator: Aug 13, 2013
5. Aug 31, 2010

### HallsofIvy

Staff Emeritus
Re: Finding the Equation of Tangent line on cos wave!!!

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

6. Aug 31, 2010