Multiple choice The ratio of the radius of two circles is 5:4. What is the ratio of their areas? $5:4$ $25:16$ $6:7$ $9:13$ Reveal answer Fill a bubble to check yourself B Correct answer Explanation Area of a circle is πr². If radii are in ratio 5:4, areas are in ratio π(5)²:π(4)² = 25:16. The ratio of areas is the square of the ratio of radii.