Find all points on the graph of the function f(x) = 2cos(x) + cos(x)^2 at which the tangent line is horizontal. I found the derivative to be -sinx(cosx + 2).

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- Feb 11th 2010, 10:18 PMBugzLooneyhorizontal tangent, set it to zero, now what?
Find all points on the graph of the function f(x) = 2cos(x) + cos(x)^2 at which the tangent line is horizontal. I found the derivative to be -sinx(cosx + 2).

- Feb 11th 2010, 10:19 PMmr fantastic