If the diameter of a circle is tripled times, the circumference is
a. multiplied by 3.
b. multiplied by 6.
c. multiplied by 9.
d. multiplied by 12.
a. The formula for evaluating the circumference of a circle is πd. If the radius is tripled, the diameter is also tripled. The new circumference is π3d. Compare this expression to the original relation; with a factor of 3, the circumference is multiplied by 3.