Two circles are concentric. A chord of the larger circle is tangent to the smaller. If the area of the annulus is
A, express the length of the chord in terms of A.

Dear student

Let the radius of the smaller circle be rand radius of the larger circle be RGiven,  area of annulus =Aand also we know that, A=πR2-πr2A=πR2-r2R2-r2=AπR2-r2=Aπ  ...(1)Now consider OO'BBy pythagoras theoremOB2=OO'2+O'B2R2=r2+O'B2R2-r2=O'B2R2-r2=O'BSo, AB=2O'BAB=2×Aπ   from (1)
Regards

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