SOLUTION: find the exact value of cos 405 degrees oftthis trigonometric function

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Question 972825: find the exact value of cos 405 degrees oftthis trigonometric function
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Start with the unit vector of the unit circle
at 0 degrees
Then rotate 360 degrees back to where you started
Then rotate 45 degrees more.
+360+%2B+45+=+405+
You are in the 1st quadrant where the cosine is positive
+cos%28+405+%29+=+cos%28+45+%29+
+cos%28+405+%29+=+sqrt%282%29+%2F+2+