Question

Use the unit circle to find the inverse function value in degrees.

cos -1((sqrt)3/2)

A. 60°
B. 30°
C. 240°
D. 150°

Answer 1

can someone just show me how to get my answer without telling it to me?

Answer 2

@satellite73 @zepdrix

Answer 3

@Loser66

Answer 4

\[\Large\bf\sf \cos330^o\quad=\quad \cos30^o\quad=\quad \frac{\sqrt3}{2}\]

Answer 5

The inverse cosine function, in order to be a function, has it's domain restricted from 0 to pi.

So the inverse cosine can only produce angles in the first 2 quadrants.
Which angle do we want? 330 or 30 degrees?

Answer 6

30 degrees?

Answer 7

Woops, domain restricted from -1 to 1 I think I meant to say :O
Err blah it's not too important to what we're doing...

Answer 8

Yes, because 30 degrees is in the first quadrant.
330 degrees is in the 4th quadrant, which is not in the range of our function arccosine, which only gives us angles in the first 2 quadrants.

Answer 9

Ok so now what do we do?

Answer 10

We choose B silly! :3

Answer 11

*facepaw* Oh XDD

Answer 12

Sorry i didn't pay attention to my answers i put

Answer 13

heh