Posted by **Kayla** on Thursday, March 18, 2010 at 11:05am.

Hi I need to solve this question for x, where 0<x<2pi. The question is 2cos^2 x + cos x =1. Then it asks me to wrtie a general solution for it. I really don't understand how to do any of this. I just started this unit and I'm finding it so difficult. Any help would be so much appreciated.

- trig -
**drwls**, Thursday, March 18, 2010 at 11:13am
Use algebra to solve for the variable cos x. The equation we are solving will look simler if give that cos x a new name, y.

2y^2 +y -1 = 0

That equation can be factored as follows:

(2y -1)(y+1) = 0

This means that y = 1/2 or y = -1. Both are solutions. The corresponding angles are:

60 degrees, 300 degrees and 180 degrees.

## Answer This Question

## Related Questions

- trig 30 - Please help I need to solve the following question for x, where 0<x...
- Math - Hi, I'm really having problems with this question, can someone please ...
- Trig--check answer - Solve the equation of the interval (0, 2pi) cosx=sinx I ...
- Math - Solving Trig Equations - What am I doing wrong? Equation: sin2x = 2cos2x ...
- Trig - If cosx = 10/19 an pi < x < 2pi, find the exact value of cos x/2 ...
- Math - Solving for Trig Equations - Solve the following equation for 0 less than...
- trig - 2sin(x)cos(x)+cos(x)=0 I'm looking for exact value solutions in [0, 3&#...
- Trig....... - I need to prove that the following is true. Thanks (2tanx /1-tan^x...
- RESPONSE to PreCalc Question - h t t p : / / w w w . j i s k h a . c o m / d i s...
- trig - e.g. tan 315 = -1, does that work in our equation ?? Yes, thank you again...

More Related Questions