Let ABC be an equilateral triangle inscribed in circle O. M is a point on arc BC. Lines AM, BM, and CM are drawn. Then AM is:
[asy]defaultpen(linewidth(.8pt));
unitsize(2cm);pair O = origin;
pair B = (1,0);
pair C = dir(120);
pair A = dir(240);
pair M = dir(90 - 18);draw(Circle(O,1));
draw(A--C--M--B--cycle);
draw(B--C);
draw(A--M);
dot(O);label("A",A,SW);
label("B",B,E);
label("M",M,NE);
label("C",C,NW);
label("O",O,SE);[/asy]<spanclass=′latex−bold′>(A)</span>equal to BM+CM<spanclass=′latex−bold′>(B)</span>less than BM+CM<spanclass=′latex−bold′>(C)</span>greater than BM+CM<spanclass=′latex−bold′>(D)</span>equal, less than, or greater than BM+CM, depending upon the position of M<spanclass=′latex−bold′>(E)</span>none of these