Math - Solving for Trig Equations

posted by .

For the following equation, why cannot I not solve it? I keep getting an error.

--
2cosx - 3 = 0
--

I first isolated for "x"
2cosx-3 = 0
(2cosx/2) = (3/2)
x = cos^-1(3/2)
x = error? why?

--
My textbook answer:
30 and 330 degrees
--

  • Math - Solving for Trig Equations -

    Make sure you copied the question correctly.
    The way it stands
    cos x = 3/2 has indeed no solution

    (the sine and cosine function does not exceed a value >1 or < -1

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. math

    tanx+secx=2cosx (sinx/cosx)+ (1/cosx)=2cosx (sinx+1)/cosx =2cosx multiplying both sides by cosx sinx + 1 =2cos^2x sinx+1 = 2(1-sin^2x) 2sin^2x + sinx-1=0 (2sinx+1)(sinx-1)=0 x=30 x=270 but if i plug 270 back into the original equation …
  2. Trig

    cos2x(2cosx+1)=0 Solve for x.
  3. trig

    prove that (2cosx+1)(2cosx-1)= 1 +2cos2x
  4. trig

    how do you graph the equation y=-2cosx?
  5. Calculus

    Determine the concavity and find the points of inflection. y=2cosx + sin2x 0≤x≤2pi y'=-2sinx + 2cos2x y"=-2cosx-4sinx How do I find the IP(s)?
  6. Trig

    Solve for x in the interval [0,2pi) sin^2x+2cosx=2
  7. Mathj C30

    Solving Equations Containing Circular Functions : Solve 2cosx sinx + sinx = 0 when x is between 0 and 2pi
  8. Math

    Find the limit of (2cosx+3cosx-2)/(2cosx-1)as x tends to pi/3.
  9. Pre Calculus

    Having trouble verifying this identity... cscxtanx + secx= 2cosx This is what I've been trying (1/sinx)(sinx/cosx) + secx = 2cosx (1/cosx)+(1/cosx) = 2 cosx 2 secx = 2cosx that's what i ended up with, but i know it's now right. did …
  10. derivatives

    x^2cosx-2xsinx-2cosx

More Similar Questions