question_answer

The perimeter (in cm) of a square circumscribing a circle of radius a cm, is:    (CBSE 2011)

A) \[4a\]

B) \[5a\]

C) \[8a\]

D) \[10a\]

Correct Answer: C

Solution :

[c] Given, radius of circle \[=a\,cm\]

\[\therefore \]  Diameter \[=2a\,cm\]and side of a square

\[AB=BC=CD=DA\]

= Diameter \[=2a\,cm\]

Hence, the required perimeter     \[=4(side)=4(2a)=8a\,cm\]