The ratio of areas of two circles is 81 : 121. What will be the ratio of their circumferences ?
Answer & explanation
Correct answer: option 1
Area of circle = \(\Pi \)\( {r }^{2 } \)
Circumference of a circle = 2\(\Pi \)r
⇒ Ratio of circles A and B = 81 : 121
⇒ \(\Pi \)\( {r }^{2 } \)A = 81, \(\Pi \)\( {r }^{2 } \)B = 121
⇒ \(\Pi \)r A= 9, \(\Pi \)r B = 11.
⇒ Circumference ratio = 2\(\Pi \)9 : 2\(\Pi \)11
⇒ 9 : 11.