The radius of the circle increased by 6cm from 3cm, and the area of the circle increased by () square centimeter A. 27πB. 36πC. 72πD. 9π
3 + 6 = 9 (centimeter) π × 92 - π × 32 = 81 π - 9 π = 72 π (square centimeter) answer: the area of circle increases by 72 π square centimeter