Analysis of the voltage in certain types of circuits involves terms of the form sin(nw^0t-90 degrees) where n is a positive integer, w0 is the frequency of the voltage, and t is time. Use an identity to simplify this expression.
A.cscnw0t
B.-cscnw0t
C.cosnw0t
D.-cosnw0t
Subtracting 90° from the argument of the sine function shifts its graph 90° to the right, putting the negative peak on the y-axis. That corresponds to the negative cosine function, choice D.
