Question

Solve: $\frac{{\cos }^2\theta }{{\cot }^2\theta }-{\cos }^2\theta =3$

Answer 1

$\frac{co{s}^2\theta }{co{t}^2\theta }-co{s}^2\theta =3\Rightarrow \frac{co{s}^2\theta }{\frac{co{s}^2\theta }{si{n}^2\theta }}-co{s}^2\theta \Rightarrow si{n}^2\theta -co{s}^2\theta =cos2\theta$

$\therefore cos2\theta =3$ (not possible)