Question

on decreasing the radius of circle by 30% it's area is decreased by

30%

60%

45%

none​

Answer 1

sorry dude....your all options are wrong.......right answer is 51%

$decreased \: area \: = total \: area - remained \: area \\ = \pi {r}^{2} - \pi {r |2| }^{2} \\ \\ = \pi({ \frac{100}{100})}^{2} - \pi{\frac{70}{100}}^{2} \\ = 1 - 0.49 \\ = 0.51 \\ = 51\%$

hope it will help you.....:)

Answer 2

let the radius of circle be R

Area of the circle= 3.14 * R^2

Now, radius is decreased by 30%

New radius of circle would be 0.7R

Hence,

New Area= 3.14*(0.7R)^2

New Area= 0.49 * 3.14*R^2

Therefore, New area of the circle would be 51% less than that of original one.

so, option D is correct..

hope it helps you ☺☺