Answer: the answer is c
Step-by-step explanation:
We know that:

is an equation of a circle.
When we substitute x and y (from the pairs we have), we'll get a system of equations:

and all we have to do is solve it for a, b and r.
There will be:

From equations (II) and (III) we have:

and from (I) and (II):

Now we can easly calculate a and b:

Finally we calculate

:

And the equation of the circle is:
Answer:
210
Step-by-step explanation:
Answer: The answer is 81.
ANSWER

EXPLANATION
Let R be the radius of the bigger circle and r, be the radius of the smaller circle.
Then their ratio is given as,

We can rewrite it as fractions to get,

We make R the subject to get,

The area of the bigger circle can be found using the formula,

This implies that,


But it was given in the question that, the area of the bigger circle is 27π.

We divide through by 9π to get,

This means that,

The area of the smaller circle is therefore
