A:u
B:up to
C:up against
D:up with
如图,△ABC中,∠C=90°,CA=CB,点M在线段AB上,∠GMB=12∠A,BG⊥MG,垂足为G,MG与BC相交于点H.若MH=8cm,则BG= ____m.
已知函数f(x)=lnx﹣mx+m,m∈R.