c# math cos different values from calculator

Question

I am trying to do a precision type of program where i encountered values there were wrong and have been able to pinpoint the problem area. The Math.cos values differ from the calculator values and how can i correct this for instance

Math.Cos(28.545742)

gives the value -0.963394351754924 but on all other calculators it gives me a correct value of 0.8784358937 which is perfect since it completes the expected program output. How can I get Math.Cos to give me the answers I want? and this is my first time messing with C# math functions.

Answer 1

Math.Cos() is using radians while your calculator is using degrees. A simple way to convert from degrees to radians is degrees*(pi/180).

In code:

Math.Cos(28.545742*(Math.PI/180))

Answer 2

You need to specify the angle in radians, not degrees.

There are 2*pi radians in a circle, and 360 degrees. So to convert degrees to radians, divide by 360 and multiply by 2*pi (simplified: multiply by pi/180 ):

Math.Cos(28.545742 * Math.PI / 180f)

Will give you the correct answer.

Answer 3

Math.Cos function takes values in radians.

Here is the detailed explanation on MSDN site about the function.