Find, to the nearest degree, all values of theta in the interval 0° ≤ theta < 360°
that satisfy the equation 3 cos 2theta + sin theta – 1 = 0.
At:
Wolfram|Alpha
enter the command:
plot 3 cos(2x) + sin(2x) - 1 for x between 0 and 360 degrees
it looks like the equation has four zeros in your interval. Use your graphing calculator to approximate them.
Good luck!