Find the rate of change of the total surface area of a cylinder of radius r and height h, when the radius varies.
Total Surface Area of Cylinder = 2 π r2 + 2 π r h
Given: Radius of the Cylinder varies.
Therefore, We need to find 
where S = Surface Area of Cylinder and r = radius of Cylinder.
Hence, Rate of change of total surface area of the cylinder when the radius is varying is given by (4 π r + 2 π h).
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