i'm stuck on this one:

Prove that || z1|-|z2|| £ |z1-z2|

Thanks!

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- April 2nd 2009, 08:02 PMmorganfortwist on the triangle inequality proof
i'm stuck on this one:

Prove that || z1|-|z2|| £ |z1-z2|

Thanks! - April 3rd 2009, 03:42 AMOpalg
The usual triangle inequality tells you that , and hence . The same inequality with and interchanged gives . The two inequalities together give .