how do you find tan(cos-1(1/3)) if it's not on the unit circle?

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- Nov 8th 2008, 02:29 PMFinalFantasy9291unit circle
how do you find tan(cos-1(1/3)) if it's not on the unit circle?

- Nov 8th 2008, 02:46 PMPlato
Let $\displaystyle \phi = \arccos (1/3)$ so $\displaystyle \cos (\phi ) = 1/3$.

Look at the diagram. What is $\displaystyle \tan (\phi ) = ?$