作业帮A sheet of tin is cut so as to form a circular ring that has an area of 18 square inches.The total outer and inner perimeters of the ring measure 36 inches.Find the inner radii and the outer radii of the ring.Use area of circle=派r^ circumference=2
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A sheet of tin is cut so as to form a circular ring that has an area of 18 square inches.The total outer and inner perimeters of the ring measure 36 inches.Find the inner radii and the outer radii of the ring.Use area of circle=派r^ circumference=2
A sheet of tin is cut so as to form a circular ring that has an area of 18 square inches.The total outer and inner perimeters of the ring measure 36 inches.Find the inner radii and the outer radii of the ring.Use area of circle=派r^ circumference=2派r and 派=3.14.Give the answer to three significant figures
A sheet of tin is cut so as to form a circular ring that has an area of 18 square inches.The total outer and inner perimeters of the ring measure 36 inches.Find the inner radii and the outer radii of the ring.Use area of circle=派r^ circumference=2
pi*(r1^2-r2^2)=18 and 2*pi*(r1+r2)=36,第一个公式按平方差展开,再代入第二个公式,可以得到r1=r2+1,代回第二个公式可得：r1=(19+pi)/2pi,r2=(19-pi)/2pi