Two equal arcs of different circles C₁ and C₂ subtend angles of 60° and 75° respectively, at the centres. What is the ratio of the radius of C₁ to the radius of C₂?
Answer
The correct answer is D: 5:4. Arc length = rθ. Equal arcs: r₁·60 = r₂·75, so r₁/r₂ = 75/60 = 5/4.