Answer: common difference is 14
Step-by-step explanation:
a,a+d,a+4d
7,7+d,7+4d
(7+d)/7=(7+4d)/(7+d)
(7+d)(7+d)=7(7+4d)
49+14d+d^2=49+28d
d^2-14d=0
d(d-14)=0
d=0 or d-14=0
d=14
Answer:
1
circumference =2×pi×r
18/2=9(r)
so...2×pi×9
=54..5
