isn't tan(10pi/3) supposed to be sqrt(3).. ?

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- Feb 12th 2008, 11:55 AMweasley74tan(10pi/3)
isn't tan(10pi/3) supposed to be sqrt(3).. ?

- Feb 12th 2008, 11:58 AMJhevon
- Feb 12th 2008, 12:03 PMjanvdl
- Feb 12th 2008, 12:07 PMweasley74
yeah, calculators not allowed..

- Feb 12th 2008, 12:09 PMjanvdl
- Feb 12th 2008, 12:12 PMJhevon
no calculators, no problem!

you should know $\displaystyle \tan \frac {\pi}3$ by heart, or know how to get is from the sine and cosine of pi/3

then, by reference angles, $\displaystyle \tan \frac {k \pi}3 = \pm \tan \frac {\pi}3$

the sign depends on what quadrant the angle $\displaystyle \frac {k \pi}3$ is. $\displaystyle \frac {10 \pi}3$ is in the third quadrant, so we take the plus sign