Example  1.5.  To produce an example of which Figure 1.9 is a reasonable illustration, we let  .  Then    and  .  Clearly,  ;  hence  .  In this case, we can verify the triangle inequality without recourse to computation of square roots because  

        ,  
thus
            .  

Explore Solution 1.5.

Compute .

(c) 2006 John H. Mathews, Russell W. Howell