Question

if raddi of two concentric circle are 28 cm and 18 cm respectively. If the perimeter and area of circle are numerically equal,then find the radius of the circle​

Answer 1

Step-by-step explanation:

Let the radius of required circle =r cm

Radius of 1st circle r

1

=9 cm

Radius of 2nd circle r

2

=19 cm

As per the question

Circumference of the required circle = Sum of circumference of two circles

Circumference of small circle =2πr

1

=2π×9

=18π

Circumference of small circle =2πr

2

=2π×19

=38π

Now,

Circumference of the required circle = Sum of circumference of two circles

2πr=18π+38π

2πr=58π

r=

2π

56π

r=28 cm

Hence, radius of new circle is 28 cm.

Answer verified by Toppr