Question

What is the difference between the circumference of the outer circle and the circumference of the inner circle? Leave your answer in terms of π.


A. 2π m
B. 4π m
C. 7π m
D. 18π m

Answer 1

Given :

• Radius of outer circle = 9 m.
• Difference between the radius of the outer circle and radius of inner circle = 2 m.

To find :

• Difference between the circumference of the outer circle and the circumference of inner circle.

Solution :

Formula Used :-

${\boxed{\bold{Circumference\:of\: circle=2\pi\:r}}}$

★In case of outer circle,

• Radius = 9 m

Circumference of outer circle,

= 2πr

= (2π × 9) m

= 18π m

★ In case of inner circle ,

• Difference between the radius of the outer circle and radius of inner circle = 2 m.

Then,

Radius of inner circle = (9-2) m = 7 m

Circumference of inner circle ,

= 2πr

= (2π × 7) m

= 14π m

So, the difference between their circumference,

= (18π - 14π) m

= 4π m

Therefore, the difference between the circumference of the outer circle and the circumference of inner circle is 4π m.

${\boxed{\sf{Option\:(B)\:is\: the\: correct\:answer}}}$

Answer 2

✯✯ QUESTION ✯✯

What is the difference between the circumference of the outer circle and the circumference of the inner circle? Leave your answer in terms of π.

A. 2π m

B. 4π m

C. 7π m

D. 18π m

━━━━━━━━━━━━━━━━━━━━

✰✰ ANSWER ✰✰

➜Using Formula : -

$\longrightarrow{\small{\boxed{\boxed{\bold{\purple{\sf{Circumference\:of\:Circle=2πr}}}}}}}$

➜For Outer Circle : -

$\longrightarrow{Radius=9m}$

Now ,

$\longrightarrow{Outer\:Circle=2πr}$

$\longrightarrow{2π(9)}$

$\longrightarrow{18πm}$

As Given that difference between Radius of Outer and Inner Circle is 2m. So,

$\longrightarrow{Radius(Inner\:Circle)=9-2=7m}$

➜For Inner Circle : -

$\longrightarrow{Inner\:Circle=2πr}$

$\longrightarrow{2π(7)}$

$\longrightarrow{14πm}$

➜Difference between their circumference is : -

$\longrightarrow{Outer\:Circumference-Inner\:Circumference}$

$\longrightarrow{18π-14π}$

$\longrightarrow{4πm}$

☛So,Option B) is Correct .....