Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Frustrating excel problem with COS

  1. Feb 27, 2012 #1
    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:


    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.


  2. jcsd
  3. Feb 27, 2012 #2
    No worries, figured I can get it to change by adding:

    *(Pi()/180) on the end
  4. Feb 27, 2012 #3


    User Avatar

    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)).
  5. Mar 3, 2012 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook