The radius of the blue circle is 2+1 = 3 times the radius of the red, since the total diameter is 6r, divide 2 = 3.
πr^2 is the area of a red, divided by 2, and multiplied by 3 for the 3, so \(\frac{3πr^2}{2}\).
The radius of the blue is 3r, so (3r)^2 * π /2 is \(\frac{9πr^2}{2}\).
Since they are both divided by two, that is of little importance. They are all (number) times r^2 π, so r and π doesn't matter. The red is 3rπ, second is 9rπ, so The ratio is 3:9 = 1:3, red:blue
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