Bán kính hình tròn mới là:100%-20%=80%

S mới:80x80=6400=64%(ko tính số pi vì tính vào nó cũg ra như vậy)

s ban đầu: 44,46:64x100=69.46875

Hinh nhu ban tra loi sai roi thi phai sao so lai to the

( 100% * 100% ) - ( 80% * 80% ) = 36%

Diện tích hình tròn là : 44,46 : 36% = 1,235 = 123,5m2

Đáp số : 123,5m2

cậu bị điên à

Coi bán kính hình tròn cũ là : 100% , Bán kính hình tròn mới là : 80%

Diện tích giảm đi chiếm :

  100 % x 100 % - 80% x 80 % = 36 %

Diện tích hình tròn cũ là :

   44.46 x 36 x 100 = 123.5 ( \(m^2\))

              Đáp số : 123.5 \(m^2\)

Dang ia mot tran

Cách giải:
(100% x 100%) - ( 80% x 80%) = 36%
Diện tích hình tròn là:
44,46 : 36% = 1,235 = 123,5 m2
Đáp số : .......

123.5 bạn nhé !

Chúc bạn học giỏi !

\(123,5\)\(m^2\)1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000%