The perimeter difference between the two circles is 94.2cm, and the radius of the big circle is twice the diameter of the small circle

Let the radius of small circle be r, and the radius of large circle be r, then r = 4R
2×π×4r－2×π×r＝94.2
The solution is r = 5
S＝π[（4r）²＋r²]＝1334.5

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