SOLUTION: simplify cos(x+π)

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Question 613947: simplify cos(x+π)
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
cos%28x%2Bpi%29
Just use the cos(A+B) formula:
cos(A+B) = cos(A)cos(B) - sin(A)sin(B)
with "A" being "x" and "B" being "pi":
cos%28x%2Bpi%29+=+cos%28x%29cos%28pi%29+-+sin%28x%29sin%28pi%29
Since cos%28pi%29+=+-1 and sin%28pi%29+=+0 this simplifies: