由 ---- 於 星期六 六月 21, 2003 1:43 pm
this question is so strange
sinA + sinB + cos(A+B)
=sinA + sinB + sin(90+A+B)
<= 3sin{[2(A+B)+90]/3}
<= 3sin{[2*180+90]/3}
=3sin150
=3/2
is this a proof?
Edited: I know what's going on now, I forgot that it should be bounded as [0,270]~
Edited 2: This is wrong, as the function is not strictly convex within [0,270]