In Exercises 9–16, evaluate the trigonometric function at the quadrantal angle, or state that the expression is undefined.csc 𝜋

Quadrantal angles are angles that are multiples of 90 degrees (or π/2 radians), which correspond to the axes in the unit circle. These angles include 0, π/2, π, 3π/2, and 2π. At these angles, the sine and cosine functions take on specific values, which are essential for evaluating trigonometric functions like cosecant.

The cosecant function, denoted as csc, is the reciprocal of the sine function. It is defined as csc(θ) = 1/sin(θ). Therefore, to evaluate csc at a specific angle, one must first determine the sine of that angle. If the sine is zero, the cosecant is undefined, as division by zero is not possible.

Evaluating trigonometric functions involves determining the value of the function at a given angle. For quadrantal angles, this often requires knowledge of the unit circle and the specific sine and cosine values at those angles. Understanding how to find these values is crucial for solving problems involving trigonometric functions.