The ratio of the diameters of two circles is $3:4$, then find the ratio of their circumferences.

Given: The ratio of the diameters of two circles is $3:4$.

To do: To find the ratio of their circumferences.

Solution:

Let $d_1$ and $d_2$ are the diameters of the two circles.

Here, as given, ratio of the diameter of two circles, $d_1:d_2=3:4$

Ratio of circumference$=2\pi r_1:2\pi r_2$    [$r_1$ and $r_2$ are the radii of the circles ]

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$=\pi d_1:\pi d_2$

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$= d_1:d_2$

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$=3:4$

Thus, the ratio of the circumference of the two circles is $3:4$.