problem with Math.Cos(bouble a)

Question

Maybe it sounds supidly but I don't andestand why functions from C# Math library return incorrect values for exmple Math.Cos(90)=-0.44807361612917 instead ziro like problem observed in Math.Sin and Math.Tan Thanks

bilnaad · Answer

That's because the Cos() function doesn't treat the double value as a degree. It is measured in radians. So the only thing you need to do is convert the desired degree to a radian and pass the radian as a parameter. I believe the formula is like this( it's a while ago I did this ) double radian = degree * (Math.PI / 180); and back double degree = radian * (180 / Math.PI); Good luck