Ok so we know that the distance around the circle (or circumference) is equal to the diameter times pi.
This means that

d being the diameter,
This means that:

= 12.00028271
= 12 m
So the diameter of the circle is 12 metres.
Hope this helped
Answer:
ABC is isosceles
Step-by-step explanation:
1/3(21 - 3a) = 6 - a
7 - a = 6 - a
7 = 6
Therefore, the equation has no solution.