Question

find the radius of a circle whose circumference is 6.28cm​

Answer 1

Answer:

circumference=2πr

6.28=2×22/7×r

6.28×7/22×2= r

radius=0.99

Answer 2

Answer:

The radius of the circle is $1$ cm.  

Step-by-step explanation:  

In context to the question asked,    

We have to find the radius of a circle,  

As per data given in the question,    

We have,  

Circumference = $6.28$ cm  

For calculating radius of a circle,  

The formula to be used for,  

Circumference of circle = $2\pi r$  

By substituting the values,  

$=> 6.28= 2\times \frac{22}{7} \times r$

Expressing $(2\times \frac{22}{7} )$ as a single fraction,

$=> 6.28 =\frac{2\times 22}{7} \times r$

Multiply $2$ and $22$ to get $44$.

$=> 6.28 = \frac{44}{7}\times r$

Swap sides so that all variable terms are on the left-hand side.

$=> \frac{44}{7}\times r= 6.28$

Multiply both sides by $\frac{7}{44}$, the reciprocal of $\frac{44}{7}$,

$=> r=6.28\times \frac{7}{44}$

Convert decimal number $6.28$ to fraction $\frac{628}{100}$.

Now, Reduce the fraction $\frac{628}{100}$  to the lowest terms by extracting and canceling out $4$.

$=> r = \frac{157}{25} \times (\frac{7}{44})$

Multiply $\frac{157}{25}$ times $\frac{7}{44}$  by multiplying numerator times numerator and denominator times denominator.

$=> r=\frac{157\times 7}{25\times 44}$

Multiply the terms in the numerator as well as the denominator,

$=> r=\frac{1099}{1100}$

$=> r = 0.99$ ≈ 1cm

Hence radius of the circle is $1$ cm.