(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

sinx cos2x=1

x is greater than or equal to 0 and less than 2pi

2. Relevant equations

What I used:

1-2sin^{2}x

cos^{2}x-sin^{2}x

but there might be one that I didn't and should have...

3. The attempt at a solution

Basically I have substituted to the point that I can, I feel pretty bad since this is a review..

sinx cos2x=1

sinx (1-2sin^{2}x)=1

basically didn't know where to go from there..

and

sin cosx=1

sinx (cos^{2}x-sin^{2}x)=1

sinx(cos^{2}x)-sin^{3}x=1

sinx(1-sin^{2}x)-sin^{3}x=1

sinx-sin^{3}x-sin^{3}x=1

And that one stopped there...

we are supposed to only use trigonometric identities, nothing more nothing less; and once again I don't understand how I can not get this since it is a review..

Thanks

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# Help! solving by using trig identity

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