# Homework Help: Tangent Line and Coordinates of Trigonometric Function

1. May 1, 2010

### gabyoh23

1. The problem statement, all variables and given/known data

There are infinitely many points on the curve y = $$\frac{sin x}{\sqrt{2}- cos x}$$ at which the tangent line to this curve is horizontal. Find the x- and y-coordinates of one such point.

2. Relevant equations

y' = slope of the tangent line
Etc., etc.

3. The attempt at a solution
I know you have to take the derivative of the given equation, and at first, I tried using the quotient rule, but I got nowhere with that. Then I tried rationalizing the $$\sqrt{2}$$, but that didn't really get me anywhere either. I also have no idea how to find the x- and y-coordinates.

All help is greatly appreciated!

2. May 1, 2010

### Squeezebox

Nothing needs to be done with $$\sqrt{2}$$, it is a constant. What's the derivative of a constant? (btw, $$\sqrt{2}$$ is an irrational number which is why you couldn't rationalize it.)

The coordinates are the x and y-values of the function and y=f(x) so, (x,y)=(x,f(x))

3. May 1, 2010

### Tedjn

To the OP, please show us your work in taking the derivative using the quotient rule. I did the same and got a particularly pleasing answer.

4. May 2, 2010

### gabyoh23

I got something like $$\frac{1-cos^2(x)}{2-cos^2(x)}$$.
I'm not sure if this right at all. My prowess with the quotient rule is shoddy at best.