# Homework Help: How to determine the point of intersection of sine and cosine?

1. Mar 14, 2007

### linuxux

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

Im not sure how to start this question: determine the points of intersection between $$y=sin x$$ and $$y=cos 2 x$$ for x between 0 and pi.

3. The attempt at a solution

First thing that comes to mind is the eqaute the two, but i dont know how that helps me?

2. Mar 14, 2007

### dextercioby

3. Mar 14, 2007

### HallsofIvy

Particularly an indentity that says cos(2x) is equal to something.

4. Mar 14, 2007

### linuxux

thanks ive got it now, but is the only point of intersection in the range at $$\frac{\pi}{2}$$? i suppose i could graph it to be sure...

Last edited: Mar 14, 2007
5. Mar 14, 2007

### Gib Z

6. Mar 14, 2007

### linuxux

okay, i was solving incorrectly, they will also both be at $$30^{o}$$. i also assumed i would get a "nice" number. thanks.

Last edited: Mar 14, 2007