1 Answer

Fabi · Answer 1 · 2023-03-23T09:54:46+0000

Answer:

36%

Explanation:

Area of circle is

$\pi {r}^(2)$

If the radius is decreased by 20%. Then the radius will be

80% of the original radius.

So our radius is 0.8.

So our area is

$\pi(0.8r) {}^(2)$

$\pi(0.64 {r}^(2) )$

Since pi is constant, the radius only really matters.

We went from

$1 {r}^(2)$

to

$0.64 {r}^(2)$

So our area will decrease by 36%

Proof: Let the radius be 10.

So the area of circle will be

$\pi(10) {}^(2) = 100\pi$

Let our other radius is 8 because 8 is a 20% decrease of the orginal radius

$\pi(8) {}^(2) = 64\pi$

Next, we subtract the area to find decrease in area

$100\pi - 64\pi = 36\pi$

Since pi is constant, we can ignore it so our decrease in area is 36%

Your comment on this question: