- #1

Another1

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from problem I find \[ r = r_0 + At \] \[ x_0 = 3 + 2t\] \[ y_0 = -1 - 2t\] \[ z_0 = 1 + t\] and \[ A = (2,-2,1)\]

but i don't understand What is the distance of closest approach?

someone tell me to a formula please.