## anonymous 5 years ago Find the exact value of arccos -(sqrt(3)/(2)) without using a calculator.

1. anonymous

look at cheat sheet here http://tutorial.math.lamar.edu/cheat_table.aspx

2. anonymous

find the angle (number) whose cosine is $-\frac{\sqrt{3}}{2}$ in other words look at the unit circle on the bottom and find the angle where that is the first coordinate

3. anonymous

make sure you are looking at the upper half of the circle between 0 and pi or between 0 and 180 if you are working in degrees

4. anonymous

so I got 5pi/3 but does the arc part mean anything???

5. anonymous

arc just means ur going in reverse to figure out x in cos(x) = given value. The trig value u have is a special angle.