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I'm not quite sure how to solve this question:

cos(x) = 0.66

I am supposed to find all of the real numbers in the interval [0, 2pi] that satisfy the equation above. (Round to the nearest hundredth)


So far, I have x = cos^-1(0.66) = 0.850

 Apr 21, 2019

OK......you  found one answer  (in rads)


To find the other answer......cosine is positive in the 4th quadrant.....so.....the other angle (in rads) will be reference angle of .850 rads in the 4th quad.....so.....


2pi  - .850  ≈ 5.433 rads



cool cool cool

 Apr 21, 2019
edited by CPhill  Apr 21, 2019

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