O is the common centre of two concentric circles and radius of the bigger circle is 14 cm. Area of the smaller circle is half of the bigger circle. What is the radius of the smaller circle?
(A) 7 cm
(B)
cm
(C)
cm
(D) 10 cm
(E)
cm
It is given that radius of the bigger circle
cm
Area of the bigger circle
It is also given that area of the smaller circle is half the area of bigger circle.
Therefore, Area of the smaller circle
Let radius of the smaller circle
We have area of the smaller circle
cm
Hence, the answer is (B).
We can directly find the radius of the smaller circle given that area of the smaller circle is half of the bigger circle.
where
is the radius of the smaller circle and
is the radius of the bigger circle.
Leave a Reply