You can put this solution on YOUR website! Assuming you mean 2A = 2*Area = 23, then we can proceed.
A = 23/2 = 11.5
A = pi*r^2
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If a=b and b=c, then a=c. So we can substitute:
pi*r^2 = 11.5
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Dividing both sides by pi
r^2 = 3.66
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Take the square root (sqrt) of both sides to arrive at the answer
r = sqrt(3.66) = 1.91