Consider the system of equations $y = \cos x$ and $y = −1$. .

1. Is it possible to solve this system by substitution? By the Elimination Method? By graphing?

   Hint (a):

   Use substitution: $cos\left(x\right) = −1$. Solve for $x$.

2. List at least five possible solutions.

   Hint (b):

   List five values where the graphs intersect.

3. Consider the list of solutions you wrote in part (b) as a sequence and write a rule to represent all possible solutions.

   Hint (c):

   List your values from part (b) in order and look for a relationship.

   Answer (c):

   $x = \left(−180 + 360n\right)^\circ$ for all integers $n$

   Use the eTool below to help answer parts (a) and (b).
   Click the link at right for the full version of the eTool: 7-66 HW eTool