$($e$)$ Use Eq$.(7\mathrm{.}28)$ to determine the various components of iD$.$ Using the identity sin$2$cur $=||$ cos $2$ cot$,$ show that there is a slight shift in ID $($by how much?$)$ and that there is a second$-$harmonic component

$($i$.$e$.,$ a component with frequency $2$ co$).$ Express the amplitude of the second$-$harmonic component as a percentage of the amplitude of the fundamental. $($This value is known as the second$-$harmonic distortion.$)$