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

linuxux

## Homework Statement

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.

## The Attempt at a Solution

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

Homework Helper

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

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...

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

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