Excel's list of functions includes a number of the most common trig functions. One of these, the COS function, can be used to find the cosine of an angle measured in radians.
Note: Since most angles are measured in degrees, you might need to convert your data to radians using the RADIANS function.
The COS Function's Syntax and Arguments
The syntax for the COS function is:
= COS ( Number )
Number - the angle in radians being calculated. Options for this argument include entering the number itself or entering the cell reference to the location of the number in the worksheet.
Example Using Excel's COS Function
- Enter the number 1.047197551 - which is a 60o angle measured in radians - into cell C1
- Click on cell D1 - the location where the result of the function will be displayed
- Click on the Formulas tab of the ribbon menu
- Choose Math & Trig from the ribbon to open the function drop down list
- Click on COS in the list to bring up the function's dialog box
- Click on the Number line in the dialog box
- Click on cell C1 to enter this cell reference as the Number argument
- Click OK to close the dialog box and return to the worksheet
- The answer 0.5 should appear in cell D1, which is a cosine of the 60o angle
- When you click on cell D1 the complete function = COS ( D1 ) appears in the formula bar above the worksheet