题干

有一类随机事件概率的计算方法:设试验结果落在某个区域S中的每一点的机会均等,用A表示事件“试验结果落在S中的一个小区域M中”,那么事件A发生的概率P(A)=.有一块边长为30cm的正方形ABCD飞镖游戏板,假设飞镖投在游戏板上的每一点的机会均等.求下列事件发生的概率:

(1)在飞镖游戏板上画有半径为5cm的一个圆(如图1),求飞镖落在圆内的概率;

(2)飞镖在游戏板上的落点记为点O,求△OAB为钝角三角形的概率.

上一题 下一题 0.0难度 选择题 更新时间:2011-03-25 09:32:28

答案(点此获取答案解析)

解:(1)∵半径为5cm的圆的面积=π•52=25πcm2,

边长为30cm的正方形ABCD的面积=302=900cm2,

∴P(飞镖落在圆内)=

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