SOLUTION: FIND ALL DEGREE SOLUTIONS: sin x + cos (2x)= 0

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Question 743919: FIND ALL DEGREE SOLUTIONS:
sin x + cos (2x)= 0
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
sin x + cos (2x)= 0
sin%28x%29%2Bcos%282x%29=0
sin%28x%29%2Bcos%5E2%28x%29-sin%5E2%28x%29=0
sin%28x%29%2B1-sin%5E2%28x%29-sin%5E2%28x%29=0
sin%28x%29%2B1-2sin%5E2%28x%29=0
2sin%5E2%28x%29-sinx-1=0
(2sin(x)+1)(sin(x)-1)=0
2sin(x)+1=0
sin(x)=-1/2
x=210º+360n, 330º+360n,n=integer (Q3 and Q4 where sin<0)
or
sin(x)-1=0
sin(x)=1
x=90º+360n, n=integer