Arrange it all on one side so it's
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Now the strategy is to factor the left side to get smaller pieces that are forced to be equal to zero.
Start by recalling and , so multiply through by .
You get:
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Now remember . So:
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And now we can make our first factor, which is .
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No we know when (in your range), so that is one solution. Let's forget about that factor now and concentrate on the rest:
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Recall that , and apply this to the middle term:
Simplifies to:
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Now, remember that , so we now have:
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But refer again to the fact that . so we have:
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Apply the above identity again:
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Now solve for by just isolating it the old fashioned way. From this, you should get two more values in the interval to , making three values total because of the one we found earlier.