C# Trigonometry conversion mistake

[Anonymous]

Hi,

I am trying to evaluate a variable which is related with some trigonometric angles. However The code is leading to some different value that of the hand calculated ones. I was expecting the value of z to be 124... however code is giving some unreasonable value. This might be very silly, but I am sure I have missed some logic. Some one please help me.

My code is like this

theta = Math.Atan(l1 / l2) * 180 / Math.PI;    // converted to degrees
y = l3 / Math.Cos(theta / 2.0);
z = y * Math.Sin(theta / 2.0);

[Keith.Brown · Accepted solution]

I believe that the issue is that you are getting an answer from arctan in radians, converting it to degrees to calculate the sin and cosine.  The sin and cos functions take a parameter that is in radians not degrees.

Check out the help pages below.

atan

cos

sin

[Anonymous]

Thank you Keith Brown. Using rad instead of deg works.