I dont even know where to start on this question!!

Evaluate: Sin(2Pi/3) and Cos(2Pi/3)

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- Oct 2nd 2007, 04:45 PMredpanda11Trig Helppppp Please!!!
I dont even know where to start on this question!!

Evaluate: Sin(2Pi/3) and Cos(2Pi/3) - Oct 2nd 2007, 04:49 PMJhevon
and . those values you should know. but how do we figure out the signs? we do that by finding out what quadrant the angle is in.

Remember the mnemonic, All Students Take Calculus

if it is in the first quad: sine is positive and cosine is positive

if it is in the second quad: sine is positive and cosine is negative

if it is in the third quad: sine is negative and cosine is negative

if it is in the fourth quad: sine is negative and cosine is positive

so, what's the answer? - Oct 2nd 2007, 05:12 PMredpanda11
sin root 3/2,

cos -1/2? - Oct 2nd 2007, 05:23 PMredpanda11
sin + pi/3, cos -pi/3

- Oct 2nd 2007, 05:26 PMJhevon
- Oct 2nd 2007, 05:30 PMredpanda11
sorry i meant root3/2

and -1/2 - Oct 2nd 2007, 05:32 PMredpanda11
sorry!! i understand it to a certain extent but what if it's like tan 19pi/6 how do you know what quadrant it is in??

- Oct 2nd 2007, 05:36 PMJhevon