webwork 10.1#2

Hello Professor. I am wondering about this question. I know it's all fresh,
but I am a bit confused non the less. Isn't this a problem utilizing the
distance formula in three dimensions? If so, I am not getting nice answers.
Any suggestions?

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Yes, you need to use the distance formula in three dimensions.  The point being that the shortest distance between two points is on a straight line, so that if the three points are on a line the sum of some two distances will equal the third distance, while if they are not on a straight line the sum of any two is larger than the third.