Involving sech^{-1}((-2z)^{1/2}/(a-z)^{1/2})

Involving sech^{-1}((-2z)^{1/2}/(1-z)^{1/2}) and cos^{-1}(1/z)

Involving sech^{-1}((-2z)^{1/2}/(-z-1)^{1/2}) and cos^{-1}(1/z)