If two arcs of equal length subtend angles of 65° and 110° at the centres of two circles, the ratio of the radii r₁ : r₂ is:

For equal arcs, l = r₁θ₁ = r₂θ₂ → r₁/r₂ = θ₂/θ₁ = 110/65 = 22/13. So r₁ : r₂ = 22 : 13. (The larger angle requires a smaller radius for equal arc length.)