SOLUTION: Find the set of values of x (in radians) for which cos(x) = −1/sqrt(2), for x in [−2π, 0].

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Question 813098: Find the set of values of x (in radians) for which cos(x) = −1/sqrt(2), for x in [−2π, 0].
Answer by lwsshak3(11628) About Me  (Show Source):
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Find the set of values of x (in radians) for which cos(x) = −1/sqrt(2), for x in [−2π, 0].
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cosx=-1/√2=-√2/2
reference angle x in quadrants II and III where cos<0
x=-3π/4,-5π/4
note: cos is an even function,ie,cos(x)=cos(-x)