Consider now any triangle of diameter 1. Without loss of generality, we may take its congruent image T as BCP, with BC = 1 and ZB < ZC < ZP, since BC is the (or a) greatest side of T. Then we have ZCBP <
and BP < 1, so P e closed sector ABC a kite ABCD c R. Thus R covers every triangle of diameter 1, giving Lemma 1. Now we determine the smallest box for triangles of diameter one.