Frustrating excel problem with COS

1. Feb 27, 2012

tommy060289

Dear all,

I am currently using excel to work out some values for incident solar radiation but I am running into a rather frustrating problem when I try to do the following:

=COS(9.863)

my calculator tells me correctly this is 0.985.

however, when I put this in excel it decides it actually equals 0.905, which is obviously wrong.

I've gathered this is an issue with excel giving the answer in Rads rather than degrees but I can not figure out how you force excel to output the correct answer (in degrees) and since I have thousands of calculations it isn't feasible for me to alter every one manually.

Cheers,

Tom

2. Feb 27, 2012

tommy060289

No worries, figured I can get it to change by adding:

*(Pi()/180) on the end

3. Feb 27, 2012

Staff: Mentor

You can also use the RADIANS() function: COS(RADIANS(angle_in_degrees)).

And if you ever need to go the other way, there's a DEGREES() function: DEGREES(ACOS(x)).

4. Mar 3, 2012

Redbelly98

Staff Emeritus
Just to clarify, hopefully you realize the output result of =cos(9.863) is not in radians, it is the input number 9.863 that Excel assumes is in radians.

I didn't know that, thanks for the tip!