If 0 90^ and 4 ^2 - 4 3 + 3 = 0 then the value of is?

Answer: Option A

$$\begin{array}{rl}& 4{\cos }^2\theta -4\sqrt{3}\cos \theta +3=0\\ & \text{Hit and Trial method}\\ & \text{Put }\theta =30^{\circ }\text{option A}\\ & 4{\cos }^{2}30^{\circ }-4\sqrt{3}\cos 30^{\circ }+3=0\\ & \Rightarrow 4\left(\frac{3}{4}\right)-4\sqrt{3}\left(\frac{\sqrt{3}}{2}\right)+3=0\\ & \Rightarrow 0=0\end{array}$$