Question

if radii of two concentric circle are 28 cms and 18 cms respectively if the perimeter and the areacof the circle are numerically equal then find the radius of the circle​

Answer 1

Answer:

use this formula

Step-by-step explanation:

as we know that perimeter of a circle =2πr

area of circle =πr square

given that the perimeter of area of circle  are equal

therefore

πr²=2πr²

r²-2r=0

r[r-2]

r=0 or r=2

Answer 2

Given,

The perimeter and the area of the circle are equal.

To find,

The radius of the circle.

Solution,

We can simply solve this mathematical problem by using the following mathematical process.

Let, the radius of the circle = r unit

Area of the circle = πr² sq. unit

Perimeter of the circle (circumference) = 2πr cm

According to the data mentioned in the question,

πr² = 2πr

πr²/πr = 2

r = 2

Hence, the radius of the circle is 2 units