Answer:
0.0002778° are equivalent to one second of arc.
Step-by-step explanation:
1 degree consists of 60 arc minutes.
1 arc minutes consists of 60 arc seconds.
It can also be written as:
1 minute of arc comprise of 1/60 degree.
1 second of arc comprise of 1/60 arc minutes.
So,
1 second of arc comprise of (1/60)*(1/60) degree.
Thus,



Thus,
0.0002778° are equivalent to one second of arc.