Friday

November 21, 2014

November 21, 2014

Posted by **Anonymous** on Saturday, October 29, 2011 at 3:57pm.

Okay, so I have this problem:

cos2x( 2 cos+1)= 0

I understand I have to work the problems separately and I get cos x= 2 and cos x= 1/2

Now, what I don't understand is how this connects to pi, radians or the unit circle. If someone could explain or point me to a place with a thorough explanation, please tell me. B/c trust me, I've looked EVERYWHERE and my book/teacher doesn't really explain the theory very well.

- trig -
**Damon**, Saturday, October 29, 2011 at 4:34pmI get cos x= 2 ?????

I do not

I get

cos 2 x = 0

that means that 2x = pi/2 or 90 degrees or 2x = 3 pi/2 or 270 degrees

or x = pi/4 or 3pi/4

then

cos x = -1/2

well cos of 60 degrees or pi/3 is 1/2

so cos (180-60) = -1/2 so x =2pi/3

or 180+60 which is 5pi/3

- trig -
**Anonymous**, Saturday, October 29, 2011 at 4:39pmsry it's cos^2x

**Answer this Question**

**Related Questions**

trig--power reducing formulas - Having trouble with this problem: Rewrite the ...

TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...

Precal - I do not understand how to do this problem ((sin^3 A + cos^3 A)/(sin A...

your preciouss helpp please - how can you condense these cos^3x* cos2x^2 cos^3x...

math - Find the exact value of cos 300 degrees. thanks guys cos 300 = 1/2 = 0....

trig - I am very confused about the concepts of.. sin è = sin(180 - è) sin (180...

Math - Solving Trig Equations - What am I doing wrong? Equation: sin2x = 2cos2x ...

pre calc trig check my work please - sin x + cos x -------------- = ? sin x sin ...

Math trignometry - how can you condense these cos^3x* cos2x^2 cos^3x+ cos2x^2 ...

Math/Calculus - Please check my work and correct any errors/point out any errors...