How to proof ,

thanks

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- Dec 31st 2008, 08:47 PMSingulartrigonometry
How to proof ,

thanks - Dec 31st 2008, 09:03 PMKrizalid
You probably meant to say "how to solve" instead "how to prove," since as it's written, it just holds for certain values, in fact, it's a trig. equation.

- Dec 31st 2008, 09:05 PMLast_Singularity
cannot be proved because it is not true. I think that what you meant to ask is how to solve that equation for

Try squaring both sides and expanding:

Letting , you have

Solve for y by inspection. I see one obvious value of y such that

Then find when equals that value of y and you're done.

Note: there is more than one solution. In fact, there are infinitely many solutions to this problem because sine is a periodic function. - Dec 31st 2008, 09:06 PMSingular
owh... my mistake... sorry