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Sponsor Area
Let A be area of circle of radius r
Rate of change of area with respect to 
when r = 5, rate of change of area = 
Find the rate of change of the area of a circle with respect to its radius r when
(a) r = 3 cm (b) r = 4 cm
Let A be area of circle of radius r
Rate of change of area with respect to 
(a) When r = 3, rate of change of area = 2
× 3 = 6 cm2/cm.
(b) When r = 4, rate of change of area = 2 
× 4 = 8 
cm2/cm.
Find the rate of change of the volume of a ball with respect to its radius r. How fast is the volume changing with respect to the radius when the radius is 2 m?
Let V be volume of ball of radius r
Rate of change of volume with respect to 
When r = 2 m, rate of change of volume = 4 
(2)2 = 16 
m3/m.
How fast is the volume of a ball changing with respect to its radius when the radius is 3 m?
Let V be volume of ball of radius r.
Rate of change of volume with respect to 
When r = 3 m, rate of change of volume = 
Sponsor Area
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