The cosecant function, denoted as csc, is a trigonometric function that is the reciprocal of the sine function. In a right triangle, the cosecant of an angle is defined as the ratio of the length of the hypotenuse to the length of the opposite side. It is important in various fields, including mathematics, physics, and engineering. In terms of the unit circle, the cosecant of an angle is calculated as the reciprocal of the y-coordinate of the corresponding point on the circle. This means that if the sine of an angle is zero, the cosecant is undefined, as division by zero is not possible.