liuliuliu3
幼苗
共回答了16个问题采纳率:81.3% 举报
y = 4x/3 - 4, 4x - 3y -12 = 0
设C'(0, c)时, ⊙C与直线l相切. 此时圆心与直线l的距离d等于半径1.5.
d = |4*0 - 3c -12|/√(4² + 3²) = |3c+12|/5 = 1.5
|c + 4| = 2.5
c = -1.5, CC' = 1.5-(-1.5) = 3, t = 3/0.5 = 6 s
或
c = -6.5, CC' = 1.5-(-6.5) = 8, t = 8/0.5 = 16 s
1年前
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