Posted by **Sam** on Sunday, December 20, 2009 at 8:25pm.

I had to find the sine, cosine and tangent of -150 degrees. I got - sq. root of 3/2, -1/2, and - sq. root of 3/3. But my book has -1/2 as the sine, and -sq. root of 3/3 as the cosine. Why is this? I thought that it was thirty degrees away from the axis, so I should use pi/3.

- Trigonometry -
**bobpursley**, Sunday, December 20, 2009 at 8:51pm
No. -150deg is not PI/3

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