The reverse triangle inequality states that for vectors 
and 
in a normed space,
 |
It follows by applying the triangle inequality to 
and then interchanging 
and 
.
Reverse Triangle Inequality
See also
Normed Space, Triangle InequalityExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Reverse Triangle Inequality." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/ReverseTriangleInequality.html