t = t2 - t1 = d/v2 - d/v1 tvb now,tvbnow,bttvb# S& o8 W1 W/ |& x- z8 S- c" ?
/ |+ `" j J8 ^2 o# c" l: k7 G) Z, J0 lso answer is :公仔箱論壇: M2 `) _: G1 U: i8 D; C7 m \
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d = t * v1 * v2 / (v1-v2) |