Two voltages, V$1$ and V$2,$ are inputs to an analogue summing circuit.

V $1=$ cos$(50$ t $)$

V $2=$ sin $(50$ t $+$ $/3)$

$($a$)$ Use a compound angle identity to find the sum of these two waves, in the form

V sum$=$ C sin $(50$ t $+$ $).$