Thursday

October 23, 2014

October 23, 2014

Posted by **Josh** on Thursday, February 23, 2012 at 9:46pm.

Ive got the equation down to -cos^2(x)+cos(x)+1=0 or and it can be simplified too sin^2(x)+cos(x)=0

If you could tell me where to go from either of these two, it would be great help.. Thankyou for any responses

- Precalculus -
**Steve**, Friday, February 24, 2012 at 10:40amcos^2(x) + cos(x) = 2cos^2(x) - 1

cos^2(x) - cos(x) - 1 = 0

This is just like

u^2 - u - 1 = 0

u = [1 +/- sqrt(5)]/2

since u = cos(x) and must be less than 1,

cos(x) = (1-sqrt(5))/2

will be in QII or QIII

**Answer this Question**

**Related Questions**

Trig Help! - Question: Trying to find cos π/12, if cos π/6 = square ...

Precalculus - Use one of the identities cos(t + 2πk) = cos t or sin(t + 2&#...

math - Determine exact value of cos(cos^-1(19 pi)). is this the cos (a+b)= cos a...

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

calculus - Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x...

Calc. - Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x ln...

Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...

pre-cal - Simplify the given expression........? (2sin2x)(cos6x) sin 2x and cos ...

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

tigonometry - expres the following as sums and differences of sines or cosines ...