Trigonometry Equations. Solve for $0 \leq X \leq 360$, giving solutions correct to the nearest minute where necessary,
a) $\cos^2 A -8\sin A \cos A +3=0$
Can someone please explain how to solve this, ive tried myself and no luck. Thanks!

Divide either sides by $\cos^2A,$
$$1-8\tan A+3\sec^2A=0\implies 3\tan^2t-8\tan A+4=0$$
So, $$\tan A=\frac{8\pm\sqrt{8^2-4\cdot3\cdot4}}{2\cdot3}=2\text{ or}\frac23$$
$\implies A=n\pi+\arctan 2$ 
or $A=m\pi+\arctan\frac23$ 
where $m,n$ are arbitrary integers
