Is Cos2x the Same as Cos^2(x) in the Equation Cos2x + Cosx + 1 = 0?

[aisha]

Solve please give me some help

how would you solve this question cos2x+cosx+1=0? The cos2x is throwing me off is that the same as cos^2x? Its multiple choice and all the answers are in radian how come?

 

[AKG]

1. cos(a + b) = cos(a)cos(b) - sin(a)sin(b).
2. Do you know how to write 1 in terms of sin and cos?

 

[aisha]

1. cos(a + b) = cos(a)cos(b) - sin(a)sin(b).
2. Do you know how to write 1 in terms of sin and cos?

no i don't please help me

 

[Jameson]

\sin^{2}x + \cos^{2}x = 1

 

[blue_soda025]

cos2x is not the same as cos^2x. Use a double angle identity for that one.

 

[dextercioby]

On normal basis,u should end up with a simple quadratic equation is "\cos x"...That won't be 2 hard to solve...

Daniel.