fails:Math#acos returns the arccosine for Complex numbers
fails:Math#acos returns the arccosine for numbers greater than 1.0 as a Complex number
fails:Math#acos returns the arccosine for numbers less than -1.0 as a Complex number
fails:Math.acos returns the arccosine for Complex numbers
fails:Math.acos returns the arccosine for numbers greater than 1.0 as a Complex number
fails:Math.acos returns the arccosine for numbers less than -1.0 as a Complex number