Frustrating excel problem with COS

[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

 

[tommy060289]

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

*(Pi()/180) on the end

 

[jtbell]

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)).

 

[Redbelly98]

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.

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.

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)).

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

 

[LudusRex]

Hello Tom,

I understand your frustration with this excel problem. It seems like excel is giving you the answer in radians instead of degrees. To force excel to output the correct answer in degrees, you can use the RADIANS function. For example, instead of typing =COS(9.863), you can type =COS(RADIANS(9.863)) and this should give you the correct answer of 0.985.

Alternatively, you can also change the settings in excel to always use degrees instead of radians. To do this, go to File > Options > Formulas and under "Working with formulas", make sure the "Use radians" box is unchecked.

I hope this helps solve your frustrating excel problem. Good luck with your calculations!

Best,