The radius of the circle has increased from 6 cm to 9 cm, and the area of the circle has increased by () square cm? Explain the reason, three grams of oil Every step should be explained;;;

The radius of the circle has increased from 6 cm to 9 cm, and the area of the circle has increased by () square cm? Explain the reason, three grams of oil Every step should be explained;;;

The radius of the circle increased from 6 cm to 9 cm, and the area of the circle increased by (141.3) square cm
（9*9-6*6）*3.14=141.3
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When the radius of a circle increases from 6 cm to 9 cm, the area of the circle increases ()
A. 9 π square centimeter B. 45 square centimeter C. 45 π square centimeter

π × (92-62), = π × 45, = 45 π (square centimeter); answer: the area of the circle has increased by 45 π square centimeter

The radius of the circle increases from 6 cm to 9 cm. How many cm does the area of the circle increase

If you ask "increase to"; 9 × 9 × 3.14 = 254.34 square centimeter
If it is "increased": 3.14 × (9 × 9-6 × 6) = 141, 3 square centimeters
14 × 9 × 9-3.14 × 6 × 6 = 254.34-113.04 = 141.3 square centimeter