SOLUTION: Solve the following equation for x: cos x = -1, for the interval 0 < x < 2 pi

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Question 391229: Solve the following equation for x:
cos x = -1, for the interval 0 < x < 2 pi
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
Look at a unit circle. For any point on the unit circle, the x-coordinate represents cos%28theta%29 and the y-coordinate represents sin%28theta%29.

Since cos x = -1, the x-coordinate must be -1, and the y-coordinate must be 0 (due to the Pythagorean identity). This only occurs when x+=+pi.