4cosx + 3 = 0

1 answer

I assume we are solving.

4cosx = -3
cosx = -3/4
x must be in quadrants II or III by the CAST rule
the reference angle is 41.4°
(I took arccos .75)

so x = 180-41.4 = 138.6°
or x = 180+41.4 = 221.4°

set your calculator to radians if you want the answer in radians

Ask a New Question or answer this question.

Similar Questions

Determine the general solution of 8 cos^2x - 4cosx - 1 =0(8cos^2x - 4cosx)/8 =1/8 cos^2x - 4cosx=1/8 cos^2x/cosx =1+4cosx/cosx
1. 1 answer
Let f(x)=9sinx/2sinx+4cosx.Then 'f(x)= ((2sinx+4cosx)(9cosx)-(9sinx)(2cosx-4sinx))/(2sinx+4cosx)^2. The equation of the tangent
1. 0 answers
Complete the table of values that can be used to graph f(x)=−4cosx.(2 points) x f(x)=−4cosx 0 π2 π 3π2 2π
1. 1 answer
Complete the table of values that can be used to graph f(x)=−4cosx .(2 points) x f(x)=−4cosx 0 π2 π 3π2 2π
1. 1 answer