Posted by **Wes** on Thursday, April 22, 2010 at 8:54pm.

How do you express in terms of angles less than 90 degrees?

sin 120 degrees

cos 150 degrees

tan 280 degrees

- trig -
**Reiny**, Thursday, April 22, 2010 at 9:41pm
Always ask yourself,

1. What quadrant is the angle in? That determines the ± according to the CAST rul

2. "How far is it to the x-axis"?

sin 120° = sin60

cos150° = -cos 30

tan 280° = -tan 80°

- trig -
**victor_hery**, Friday, August 31, 2012 at 12:20am
Sin (180 - A) = sin A. (angle in degrees)

sin 120 = sin (180 - 60) = sin 60

Cos (180 - A) = - cos A

cos 150 = cos (180 - 30) = - cos 30

tan (360 - A) = - tan A,

tan 280 = tan (360 - 80) = - tan 80

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