Question

the difference between circumference and diameter of a circle is 21.4 cm. Find the radius of the circle ​

Answer 1

Answer:

Circle

Solve for radius

r=10.7cm

d Diameter

21.4

cm

Using the formula

d=2r

Solving forr

r=d

2=21.4

2=10.7cm

Answer 2

Step-by-step explanation:

Given:-

the difference between circumference and diameter of a circle is 21.4 cm.

To find:-

Find the radius of the circle .

Solution:-

Let the diameter of a circle be "d" units

d=2r units-----(1)

Radius of the circle is r units

and the Circumference of the circle=2πr units

=>C=2πr-----(2)

Now their difference=C-d

=>(2)-(1)

=>2πr-2r

=>2r(π-1)------(3)

as we know π=22/7

substitute the value of π in (3) then we get

=>2r[(22/7)-1]

=>2r(22-7)/7

=>2r(15/7)

=>30r/7

Their difference=30r/7----(4)

But according to the given problem

Their difference is given by 21.4 cm

therefore,

30r/7=21.4

=>30r=21.4×7

=>30r=149.8

=>r=149.8/30

=>r=74.9/15

=>r=4.99 cm(approximately)

Answer:-

The radius of the given circle =4.99 cm