Answer:
A satellite dish is roughly in the shape of a circle. So, the equation for cicumferance of a circle is:
C = 2[tex]\pi[/tex]r.
However, you are given the diamter in this equation. To get the radius, you will simply cut the diameter in half:
21/2 = 10.5
Now, to get the circumference of the satellite dish, you would simply plug in the numbers:
C = 2[tex]\pi[/tex](10.5)
Therefore, C = 21[tex]\pi[/tex] or roughly 65.97 meters.