>>961
これがbest
1/sinx=1/2sin0.5xcos0.5x
={(sin0.5x)^2+(cos0.5x)^2}/2sin0.5xcos0.5x
=sin0.5x/2cos0.5x+cos0.5/2xsin0.5x
あとlogf=∫f'/fを考えて簡単にできる