9.42
((x)(y) means x times y)
circumference=2 times pi times radius or 2(πr) and we notice that we can play with the distributive property and get 2(πr)=(2)(π)(r)=(π)(2r) and 2r or twice of r=diameter so 2πr=πdiamater
so
9.42=π(diameter)
divide both sides by π aproxamated in this question to be 3.14
9.42/3.14=diameter=3
the diameter is 3 feet