Question

1000 pts if u explain nicely ...

Answer 1

Let the diameter of sphere be "d"
curved surface area of sphere = 4πr2
= π (2r)2
= π(d)2
Given diameter of sphere decreases by 20%
New diameter = d - (d/5) = 4d/5
New curved surface area = π(4d/5)2
                    = (16/25) πd2
Change in surface area of sphere = πd2 – (16/25) πd2
= (9/25) πd2

decrease in curved surface area = [9/25) πd2/ πd2] x 100 = 36%
Therefore surface area decreases by 36%
The answer is best I can give

Answer 2

Answer:

Let the diameter of sphere be "d"

curved surface area of sphere = 4πr2

= π (2r)2

= π(d)2

Given diameter of sphere decreases by 20%

New diameter = d - (d/5) = 4d/5

New curved surface area = π(4d/5)2

                   = (16/25) πd2

Change in surface area of sphere = πd2 – (16/25) πd2

= (9/25) πd2

decrease in curved surface area = [9/25) πd2/ πd2] x 100 = 36%

Therefore surface area decreases by 36%