The Excel CSC function returns the cosecant of an angle — the reciprocal of the sine, 1/SIN. Excel measures angles in radians, so convert degrees with RADIANS first.
Syntax
| Argument | Description | |
|---|---|---|
number | Required | The angle in radians whose cosecant you want. Convert degrees with RADIANS(deg) or deg*PI()/180. |
How to use it
CSC is simply 1/SIN(number), introduced in Excel 2013 as a shorthand. Excel expects radians, so wrap any degree value in RADIANS():
Because cosecant is the reciprocal of sine, =CSC(x) gives exactly the same result as =1/SIN(x) — handy if you're working in an older version without CSC.
Undefined where sine is zero. At 0° (and 180°) the sine is zero, so cosecant is undefined and =CSC(0) returns a #DIV/0! error. Use angles where sine is non-zero.
Try it: interactive demo
Pick a CSC example to see the formula and its result.
Practice workbook
Frequently asked questions
What is the cosecant of an angle?
CSC(x) = 1/SIN(x). So if the sine of an angle is 0.5, its cosecant is 2.Which Excel versions have CSC?
=1/SIN(x) instead.Why does CSC(0) return an error?
=CSC(0) returns #DIV/0!. Cosecant only works where sine is non-zero.Does CSC take degrees or radians?
RADIANS(deg), for example =CSC(RADIANS(30)).Master functions like this in one day
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