Question

If two circular arcs of the same length subtend angles of $60^{\circ}$ and $80^{\circ}$ at their respective centres, then the ratio of their radii is

• A. $\frac{3}{4}$
• B. $\frac{4}{3}$
• C. $\frac{\sqrt{3}}{2}$
• D. $\frac{9}{16}$

Answer 1

Answer: (B)

$\frac{4}{3}$

Answer 2

If the radii are $r_1$ and $r_2$ then; $r_{1} \left(\frac{60 \pi}{180}\right) = r_{2} \frac{80\pi}{180}$ (= length in either case).