Write antiderivative of `tan^2x`

Explanation

`(x-1)/(xsqrt(x^2-1))dx=int(1/sqrt(x^2-1)-1/(xsqrt(x^2-1)))dx =In(x+(sqrt(x^2-1))-sec^(-1)x+c`
`therefore` The primitive =`In(x+sqrt(x^2-1)-sec^(-1)x`