請問不定積分∫1/√(1-x^2)dx=?

Let x=sinθ
dx=cosθdθ
∫1/√(1-x^2)dx
=∫cosθ/√(1-sinθ^2)dθ
=∫cosθ/cosθ dθ
=∫ dθ
=θ+ C
=sin^-1 x + C