The area of a circular sunspot is growing at a rate of 800 km^2/sec. (a) How fast is the radius growing at the instant when it equals 5,000 kilometers? HINT (See Example 1.) (Round your answer to three decimal places)
km/s
(b) How fast is the radius growing at the instant when the sunspot has an area of 810,000 square kilometers? HINT (Use the area formula to determine the radius at that instant.)
(Round your answer to four decimal places
km/s
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