Find the instantaneous form of vector A when its phasor is expressed as following, A_{s}=j 10 a_{x}+\frac{20}{j} a_{y} Box the incorrect expression: \text { (i) } \tanh j \theta=j \tan

\theta \text { (ii) }\left|e^{j \theta}-e^{-j \theta}\right|=2 \sin \theta \text { (iii) } \quad-\omega^{2} \equiv \frac{a^{2}}{a t^{2}} \text { (iv) } \ln (-1)=\pi<\frac{\pi}{2}