Example ① Points on the x-axis of the polar equation r = 1 + cosθ (cardioid).
Solution:θ=0：r=2 → (2, 0)。θ=π：r=0 → origin.
Solution:θ=0：r=2 → (2, 0)。θ=π：r=0 → origin.
Key Point
- Polar coordinates are useful for representing spirals and flower-shaped curves (rose curves).
Practice Problems
- Find r when θ=π/4 for r = 2sin(2θ).
Answers and Explanations
- Answer:2