Here you go.. hope this helps
True. A series is arithmetic if its terms come from an arithmetic sequence.
And a sequence is said to be arithmetic any of its two consecutive terms differ by a fixed difference, common to any consecutive pair.
As you can see, in this case, all terms differ by 2, so the sequence

is arithmetic, and thus the series

is arithmetic as well.
Answer: Other names for plane C can be plane EFG or plane EBF hope that helps (:
Answer = 462.738°
if i’m not wrong