The radius of any circle is defined as
Radius= Length of arc Angle subtended
Consider that the length of the arc maintained constant, then
Radius∝ 1 Angle subtended
The ratio of radii when the angle subtended are 60° and 75° respectively.
r 60 r 75 = 75° 60° = 5 4
Thus, the radii are in the ratio 5:4 .
If, in two circles, arcs of the same length subtend angles 600 and 750 at the centre, find the ratio of their radii.