Answer:
540°.
Step-by-step explanation:
On a unit circle, cos θ = -1 at 180°.
However, cos θ has a period of 2π, or 360°. This means that cos θ will equal to -1 again after 2π.
To solve for the angle:
180° + 360° = 540°. This is the next angle at which cos θ = -1.
