Answer:
A.
Step-by-step explanation:
We know that the whole length of the circumference is [tex]2 \pi[/tex].
By given, we have [tex]HJR=\frac{9}{10} \pi[/tex], and [tex]HJ=81\°[/tex] by definition of central angle.
That means
[tex]HJR=HJ+RJ\\\frac{9}{10} \pi = 81\° +RJ\\ 162\°-81\°=RJ\\RJ=81\°[/tex]
Also,
[tex]RHJ=360\° - RJ=360\° - 81\° =279\°[/tex]
Therefore, the measure of the arc RHJ is 279° which is equivalen to choice A.
[tex]\frac{31}{20}\pi = \frac{31}{20} \times 180\° = 279\°[/tex]
