How do I code this if statement

if ((Math.Cos(a)) < 0 || (Math.Cos(b) > 0 && ((Math.Cos(a) & Math.Cos(b) !> 0))

I'm trying to write this if statement. Its suppose to be if cos(a) is less than 0 or cos (b) greater than 0 and if (a) and (b) are both not greater than 0 Please how do I do it