SOLUTION: Solve it for 0<x<2pi cos(x+45)+cos(x-45)=radical 2 *both 45's are in degrees

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Question 817705: Solve it for 0 cos(x+45)+cos(x-45)=radical 2
*both 45's are in degrees
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
cos(x+45)+cos(x-45)=radical 2
Identity: cos%28s%29%2Bcos%28t%29=2cos%28%28s%2Bt%29%2F2%29cos%28%28s-t%29%2F2%29

2cos%282x%2F2%29cos%28%2890%29%2F2%29=sqrt%282%29=2cos%28x%29cos%2845%29=sqrt%282%29
2cos(x)cos(45)=√2
2cos(x)(√2/2)=√2
cos(x)=√2/√2=1
x=0
..
Check:
cos(x+45)+cos(x-45)
=cos(45)+cos(-45)=cos(x+45)+cos(x-45)=√2/2+√2/2=2√2/2=√2