Question

The area between two concentric circles of radii 7cm and 14cm is (a) 1386 sq.cm (b) 154 sq.cm (c) 616 sq.cm (d) 462 sq.cm​

Answer 1

Answer:

area between the two concentric circles is option D462

Answer 2

Answer:

The Breadth of the ring is equal to the difference between the radius of the outer circle and the radius of the inner circle

Let the radius of the outer circle be r  

2 and that of the inner circle be r  1

​ Given that the area of outer circle is 616 cm  2  

∴ πr  2

2

=616 cm  

2

 

⇒r  

2

2

​

=  

22

616×7

​

=196 cm  

2

 

∴r  

2

​

=14 cm

Also, the area of the inner circle is 154 cm  

2

 

∴ πr  

1

2

​

=154 cm  

2

 

⇒r  

1

2

​

=  

22

154×7

​

=49 cm  

2

 

∴r  

1=7 cm.

∴  The required answer ⇒r  

2 −r  

1

​

=14−7=7 cm.

Hence, the breadth of the ring is 7 cm

Step-by-step explanation:

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