# pre calc

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express the followinf trig functions in terms of an acute angle.

(a) cos 143 degrees

(b) tan 192 degrees

• pre calc -

I do these with the following steps:
cos 143
- which quadrant is it in? --- 2nd
- by CAST rule, what sign is the cosine in the 2nd? --- negative
- how far from 143º to the x-axis ? --- 37

so cos 143 = - cos 37

do the other one the same way.

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