tolong bantuin lim x->0 1-cos x / x sin x

= 1-cosx / x sinx × 1+cosx/1+cosx (kali sekawannya)
= 1 - cos^2 x/ x sinx .(1+cosx)
= sin^2 x / x sinx (1+cosx)
= 1/ 1+cos x
= 1/ 1+ cos 0
= 1/1+1
= 1/2