help geometry

Two circles have the same center (Circles which have the same center are called concentric.) The larger circle has radius 10 and the smaller circle has radius 5. Determine the area of the ring between these two circles.    

π r² (larger)  –  π r² (smaller)  =  area of ring    

π • 10² – π • 5²  =  π • 100 – π • 25  =  π • 75    

π • 75 equals approx  235.6    

The area of the ring is the area of the larger circle minus the area of the smaller cirlle.    

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