SOLUTION: Please help me find solutions over the interval [0,2π) and for all solutions if: {{{ cos2x=-1/2 }}} Sorry I'm having a lot of problems trying to figure out how many answers I'
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Question 814886: Please help me find solutions over the interval [0,2π) and for all solutions if: Sorry I'm having a lot of problems trying to figure out how many answers I'm supposed to solve for and I'm supposed to solve the corresponding range right? I need help.
Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
we are asked to find values of x over [0, 360) degrees where cos 2x = - 1/2
note that pi = 180 degrees, and the interval is open on the right
now we know that the cos 120 degrees and the cos 240 degrees is -1/2, so the cos (2*60) = -1/2 and the cos (2*120) = -1/2
x values are 60, 120, 240, 300
to see this here is the graph of y = cos 2x
each tick on the x axis is 120 degrees
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