The problem asks us to identify the curve represented by the polar equation $r = \frac{-4}{\cos \theta}$, state its eccentricity if it is a conic, and sketch the graph.
2025/6/1
1. Problem Description
The problem asks us to identify the curve represented by the polar equation , state its eccentricity if it is a conic, and sketch the graph.
2. Solution Steps
First, we rewrite the equation as .
Recall the relationship between polar and rectangular coordinates:
Substituting for , we have:
This represents a vertical line. Since a line is a degenerate conic with eccentricity .
3. Final Answer
Curve: Vertical line
Eccentricity:
Equation: