[STATEMENT]
lemma affine_hull_closed_segment [simp]:
     "affine hull (closed_segment a b) = affine hull {a,b}"
[PROOF STATE]
proof (prove)
goal (1 subgoal):
 1. affine hull closed_segment a b = affine hull {a, b}
[PROOF STEP]
by (simp add: segment_convex_hull)