Question 71

Two equal arcs of two circles subtend angle of 60° and 75° at the centre. The ratio of the radii of the two circles is

Solution

Let the radii of the two circles be $$r_1$$ and $$r_2$$ cm

Length of arcs of both circles are equal = $$\frac{\theta}{360} \times 2\pi r$$

=> $$\frac{60}{360} \times 2\pi r_1$$ = $$\frac{75}{360} \times 2\pi r_2$$

=> $$60r_1=75r_2$$

=> $$\frac{r_1}{r_2}=\frac{75}{60}=\frac{5}{4}$$

=> Ans - (A)

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