Posted by **Master chief** on Tuesday, June 7, 2011 at 4:26pm.

I get that we have to put it into radical form, but I don't understand the process. Can someone walk me through it and explain it?

arccos(-1/2)

- trig -
**Reiny**, Tuesday, June 7, 2011 at 5:12pm
you want the angle Ø so that

cosØ= -1/2

We know that if the cosØ is negative, then Ø is in either the II or III quadrant

we also know that cos 60° =+1/2

so Ø = 180-60 or 180+60

Ø = 120° or 240°

in radians it would be 2π/3 or 4π/3

your calculator will only give you the angle closest to the origin,

inter

2nd

cos

-.5

=

and you will get 120 if your calculator is set to degrees.

- trigononometry -
**aron**, Friday, June 17, 2011 at 7:52am
(12x2.17)

cos0 120.6

## Answer this Question

## Related Questions

- trig/sig figs - There are 60" in 1', 60' in 1°, and 2π radians in 360°. ...
- math,help - can someone help me plz...last problem simplify (7 + radical (5))(7...
- maht,correction - Find the area of the rectangle shown in the figure. length = ...
- Algebra 2 - Ok so I'm suppose to do this Square root of 6 ___________________ ...
- Math - Could someone please help me solve this radical equation of 2x+7-2=x It's...
- math , help,algebra - i am up to this point in my problem but i don't know what ...
- algebra - 1.what is the simplest form of the producy sqrt 50x^7y^7 * sqrt 6 xy^4...
- Math - Calculate the limit: lim(((arccos x)^(n+1))/((arccos x)^n) with x tends ...
- Chemistry - Okay so I kinda understand where to put the numbers into the formula...
- Trigonometry - Add 3+ 4i and -4+2i graphically My class got 1+ 2 radical 10 /2 ...

More Related Questions