With the usual notations, which of the following equations can measure power factor angle by using the wattmeter method?
1
\(\rm \cos^{-1}\sqrt{1+3\left(\frac{W_1-W_2}{W_1+W_2}\right)}\)
2
\(\rm \tan^{-1}\sqrt3\left(\frac{W_1-W_2}{W_1+W_2}\right)\)
3
\(\rm \cos^{-1}\sqrt3\left(\frac{W_1-W_2}{W_1+W_2}\right)\)
4
\(\rm \tan^{-1}\left(\frac{W_1-W_2}{W_1+W_2}\right)\)