Posted by Sam on .
Evaluate the sine, cosine and tangent of 7pi/3. I got 1/2, sq. root of 3/2 and sq. root of three. My book says the sine and the tangent are negative, but I don't know why? Can you explain the rule??

Trigonometry 
bobpursley,
what quadrant is it in?
2PI7PI/3=2PI2.333Pi=1/3 PI which is in the fourth quardrant. Sin, tan is negative.