lim(x→0)(cos x)∧(1/sin 2x)=?

lim(x→0)(cos x)∧(1/sin 2x)=?

f(x)=(cos x)^(1/sin 2x),lnf(x)= 1/(sin2x)ln cosx = ln(cosx)/ sin2x
lim(x->0)lnf(x)
= lim(x->0)ln(cosx)/ sin2x ln(1 + cosx-1)cosx -1
= lim(x->0)(cosx -1)/(2x)cosx -1 -x²;/2
= lim(x->0)(-x²;/2)/(2x)
= 0
原式= e^0 = 1