Question

The diameter of a sphere is decreased by 40%. By what percent its surface area
decrease.​

Answer 1

Answer:

surface area of sphere....

$\: \: \: \: \: 4(pie)r{}^{2}$

now

the relation between the diameter and the are

=

$\frac{a1}{a2} = ( \frac{d1}{d2} ) {}^{2}$

now

$\frac{a1}{a2} =( \frac{d1}{ \frac{d1 \times 60}{100} }) {}^{2} \\ \frac{a1}{a2} = \frac{100}{36}$

a2=(36a1)/100

so change in percentage of area is 36%