Use the Cofunction Identities to Find an Angle That Makes $\mathrm { V } = 158 \cos \left( 2 \pi \mathrm { ft } - \frac { \pi } { 6 } \right)$

Multiple Choice

Use the cofunction identities to find an angle that makes the statement true.
-The output voltage of a generator is given by $\mathrm { V } = 158 \cos \left( 2 \pi \mathrm { ft } - \frac { \pi } { 6 } \right)$ . Express the voltage as the sum of a sine and a cosine function.

A) $V = 79 \sqrt { 3 } \cos 2 \pi \mathrm { ft } + 79 \sin 2 \pi \mathrm { ft }$
B) $V = 79 \sqrt { 3 } \sin 2 \pi \mathrm { ft } + 79 \cos 2 \pi \mathrm { ft }$
C) $V = 79 \cos 2 \pi \mathrm { ft } + 79 \sin 2 \pi \mathrm { ft }$
D) $V = 79 \sqrt { 3 } \cos 2 \pi \mathrm { ft } - 79 \sin 2 \pi \mathrm { ft }$