Answer: Θ = π + 2kπ
Explanation:
cosΘ + 1 = 0
cosΘ = -1
Using the unit circle to help, we must determine what value of theta (in radians) makes cosine -1.
On the unit circle, there is only place where cosine is -1, and that is at π.
Since it asks to find all solutions, we use the “+ 2kπ” to account for them. (Let me know if you need an explanation of why this works/what this means.)
