Question

If $\sin A=\cos A$, then find the value of $2\tan A-2\cot A$.

Answer 1

$\sin A=\cos A2\tan A-2\cot A=\frac{2\sin A}{\cos A}-\frac{2\cos A}{\sin A}=\frac{2\sin {}^{2}A-2\cos {}^{2}A}{\cos A\sin A}=\frac{2\sin {}^{2}A-2\sin {}^{2}A}{\cos A\sin A}(\because \sin A=\cos A)=0$