Definition
A trigonometric function of an angle in a right triangle, defined as the ratio of the length of the hypotenuse to the length of the side opposite the angle. It is the reciprocal of the sine function.
Plain English
A number you get by dividing the longest side of a right triangle by the side across from the angle you're looking at. It's just the upside-down version of sine.
Context Anchor
Seen in aviation math, navigation formulas, and some older technical explanations that use trigonometry.
Derivation
From Latin co- ('complement of') and secant, from secare ('to cut'). The name reflects that it is the secant of the complementary angle. Knowing this helps explain why cosecant and sine are paired the same way cosine and secant are.
Why Pilots Care
Most pilots will not calculate cosecant during normal flying, but recognizing the term prevents confusion when reading navigation, performance, or technical math explanations.
Intuition Check
Cosecant is not the same as sine. It is 1 divided by sine, so the two values move in opposite directions.
Example Sentence 1
The radar antenna uses a cosecant-squared pattern so that targets at different ranges return signals of roughly equal strength.
Example Sentence 2
Calculating the cosecant helped find the correct distance along the hypotenuse of the course triangle.