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# Trigonometry watch

1. Having issue solving this questions:

3tan(2x) = 8/sin(2x)
in the range 0 </= x </= 180

Any help would be good, thanks!
2. (Original post by Jake_unsted)
Having issue solving this questions:

3tan(2x) = 8/sin(2x)
in the range 0 </= x </= 180

Any help would be good, thanks!
It may help to change tan2x into sin2x/cos2x and then try to make a quadratic in terms of cos2x.
3. (Original post by SeanFM)
It may help to change tan2x into sin2x/cos2x and then try to make a quadratic in terms of cos2x.
So I would have:

3(sin2x/cos2x) = 8/sin2x
4. (Original post by Jake_unsted)
So I would have:

3(sin2x/cos2x) = 8/sin2x

Yes. What can you do next?
5. (Original post by SeanFM)
Yes. What can you do next?
Could you expand the brackets, then times both sides by sin2x?
6. (Original post by Jake_unsted)
Could you expand the brackets, then times both sides by sin2x?
Don't worry about expanding, but multiplying by sin2x is the right step. Then think of any identities you know that you can apply to get everything in terms of cos.

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Updated: October 25, 2015
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