Question

3. The surface area of a sphere is 394.24 cm. If its
radius is decreased by 25%, what will be the
decrease in the surface area?
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Answer 1

Answer:

surface area=A=4πr²

⇒A∝r²

⇒dA=2rdr

⇒dA/A×100=2dr/r×100

⇒%decrease in area=2×25=50%

⇒decrease in the surface area=dA=50/100×A=1/2×394.24=197.12

Step-by-step explanation: