Question

the ratio of the radii of the two circle is 3.5 find the ratio of the circumference also find the ratio of the areas

Answer 1

Let the radius be 3x and 5x

Circumference (C1) = 2×pie×r
= 2× pie× 3x

C2 = 2×pie×5x

Ratio = C1/C2
= 2×pie×3x/2×pie×5x
= 3/5
=3:5 [ 2pie cancels with 2 pie and x cancels with x].

Area (A1) = pie× r^2
= pie×3^2
= pie 9

Area(A2) = pie× 5^2
= pie25

Ratio = pie9/pie25 [ pie cancels with pie]
= 9/25
= 9:25

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