an annulus has an outside diameter of 60 mm and an inside diameter of 20mm. determine its area

Question

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Answer 1

Area of outer circle = (Pi)(D1^2) = (3.142)(60^2) mm^2 = 11,311 mm^2

 

Area of inner circle = (Pi)(D2^2) = (3.142)(20^2) mm^2 = 1,257 mm^2

 

Therefore, area of annulus = 11,311-1,257 = 10,054 mm^2   <- - answer

 

Please understand above. Practice with different outer and inner diameters. Draw on paper and shade the annulus area.