# Thread: help me w/ trig

1. ## help me w/ trig

tan20 - cos70/cos20

thank you so much i am desperate

2. Originally Posted by desperate_on_sunday_night
tan20 - cos70/cos20

thank you so much i am desperate
Just plug it into your calculator.

(Make sure you have it set to degrees and not radians, for the record, I get zero)

3. Originally Posted by desperate_on_sunday_night
tan20 - cos70/cos20

thank you so much i am desperate
Or use the fact that $\sin 20 = \sin (90 - 70) = \cos 70$

So $\tan20 - \frac{\cos 70}{\cos 20} = \frac{\sin 20}{\cos 20} - \frac{\cos 70}{\cos 20} = \frac{\cos 70}{\cos 20} - \frac{\cos 70}{\cos 20} = 0$