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Given a line L with a coordinate system f, and three points A,B, and C with coordinates x, y, and z respectively. If A-B-C, then x-y-z.

I was thinking that I could do it this way, but I'm not quite sure.

If A<B<C, then

xy=|B-A|=B-A

because B-A>0.

Then,

yz=|C-B|=C-B

and

xz=|C-A|=C-A.

Therefore

xy+yz=(B-A)+(C-B)

= C-A

=|C-A|

= xz

so x-y-z.

If C<B<A, it follows precisely similar argument that z-y-x, which means that x-y-z as before.

Is this right? If not could you please help me?

Thank you!!

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# Homework Help: Geometry help please!

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