挑战习题
1/5单选题
难度:

1.小敏在某次投篮中,球的运动线路是抛物线y=-x2+3.5的一部分(如图),若命中篮圈中心,则他与篮底的距离l是(  )
A 3.5m
B 4m
C 4.5m
D 4.6m
提示1:
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正确答案:Qg==
6Kej77ya5b2TeT0zLjA15pe277yMLTxpbWcgd2lkdGg9NyBoZWlnaHQ9NDIgc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC9CNy9BNS9yQkFDRTFWMDkxWERPM0xNQUFBQkhrQTNuWU02NjAucG5nIj54PHN1cD4yPC9zdXA+KzMuNT0zLjA177yM6Kej5b6XeDxzdWI+MTwvc3ViPj0tMS4177yI6IiN5Y6777yJ77yMeDxzdWI+Mjwvc3ViPj0xLjXvvIw8YnI+4oi0bD0yLjUrMS41PTRt77yOPGJyPuaVhemAiULvvI4=