How to solve for theta? $$-12\sinθ-5\cosθ=0$$

Is it possible? or do I need to generate a graph? I heard the Newton Raphson Method can be used...not sure how to proceed please advise.

I'm trying to calculate the minimum and maximum values of: $y=12\cosθ-5\sinθ$

The equation above is a derivitive of $y$.
Hint: Check if $\theta=\pi/2,3\pi/2$ (I'm considering the interval $[0,2\pi]$ ) are solutions, and then divide by $\cos$ and solve for $\tan$.
y = 12cosx -5sinx

y'= -12sinx -5cosx

put y'=0

-12sinx -5cosx = 0

12sinx + 5cosx =0  (multiplied by -1 both sides )

12sinx = -5cosx

sinx/cosx=-5/12

tanx=-5/12

X = tan inverse (-5/12)

Now can you proceed?