y =ln ( ( 1+ sinx)/( 1- sinx))^1/2
1
dy/dx = -------------------------------- *d((1+sinx)/(1-sinx)^1/2
((1+ sinx)/( 1- sinx))^1/2
d((1+sinx)/(1-sinx))
dy/dx = ------------------------------------------------------------- =
( sqrt((1+sinx)/(1-sinx)))*2(sqrt((1+sinx)/(1-sinx)))
[d(1+sinx)(1-sinx) -(1+sinx)*d(1-sinx)]/(1-sinx)^2
--------------------------------------------------------------------------- =
2(1+sinx)/(1-sinx)
cosx(1-sinx) + cosx(1+sinx)
------------------------------------------------------------------ =
2( 1+sinx)(1-sinx)
cosx( 1-sinx+1+sinx)
-------------------------------------------- =
2( 1-sinx^2)
cosx/(2socsx^2) = 1/2cosx