The areas of two circles are in the ratio 4: 9. What is the ratio between their circumferences? Let the radii of the two circles be r and R, the circumferences of the circles be c and C and the areas of the two circles be a and A. Now, `a/"A" = 4/9` `=> (pi"r"^2)/(pi"R"^2) = (2/3)^2` `=> "r"/"R" = 2/3` Now, the ratio between their circumferences is given by `"c"/"C" = (2pi"r")/(pi"R"^2)` `= "r"/"R"` `=2/3` Hence, the ratio between their circumferences is 2 : 3. Concept: Circumference of a Circle Is there an error in this question or solution? > Suggest Corrections 0 |