Tell whether the sequence is arithmetic. if so what is the common difference?
1,1 1/6 1 1/3 1 1/2

a yes -1/6
b yes 1/6
c yes 6
d no

Two poles, ab and ed, are fixed to the ground with the of ropes ac and ec, as shown: what is the approximate distance, in feet, between the two poles? 6.93 feet 8.66 feet 12.32 feet 15.59 feet