Answer:
The rate of change in surface area when r = 20 cm is 20,106.19 cm²/min.
Step-by-step explanation:
The area of a sphere is given by the following formula:

In which A is the area, measured in cm², and r is the radius, measured in cm.
Assume that the radius r of a sphere is expanding at a rate of 40 cm/min.
This means that 
Determine the rate of change in surface area when r = 20 cm.
This is
when
. So

Applying implicit differentiation.
We have two variables, A and r, so:



The rate of change in surface area when r = 20 cm is 20,106.19 cm²/min.
9514 1404 393
Answer:
B. Two
Step-by-step explanation:
There are two points that are 4 inches from A and 6 inches from B.
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<em>Additional comment</em>
They are at the intersection points of circle A with radius 4 inches and circle B with radius 6 inches.
9105-4031= 5074
Step-by-step explanation:
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4.
The ratio is 3/4 for corresponding dimensions, the ratio of their surface areas is equal to the square of this ratio:

Simplify the exponent:

Cross multiply:

Divide 9 to both sides:

So the surface area of the second solid is 54 square meters.
The ratio is 3/4 for corresponding dimensions, the ratio of their volumes is equal to the cube of this ratio:

Simplify the exponent:

Cross multiply:

Divide 64 to both sides:

5.
A globe is a sphere, use the formula for the volume of a sphere:

The radius is half of the diameter, so the radius here is 40/2 = 20. Plug it in the formula, use 3.14 to approximate for Pi:

Simplify the exponent:

Multiply:
Equation a and equation c