Question
express the followinf trig functions in terms of an acute angle.
(a) cos 143 degrees
(b) tan 192 degrees
(a) cos 143 degrees
(b) tan 192 degrees
Answers
Reiny
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 143ยบ to the x-axis ? --- 37
so cos 143 = - cos 37
do the other one the same way.
cos 143
- which quadrant is it in? --- 2nd
- by CAST rule, what sign is the cosine in the 2nd? --- negative
- how far from 143ยบ to the x-axis ? --- 37
so cos 143 = - cos 37
do the other one the same way.