How Do You Systematically Solve the Equation 2cos²x - cos x = 0?

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SUMMARY

The equation 2cos²x - cos x = 0 can be systematically solved by treating it as a quadratic equation in terms of cos x. By substituting cos x with a variable, such as Z, the equation transforms into 2Z² - Z = 0. Factoring this yields Z(2Z - 1) = 0, leading to the solutions Z = 0 and Z = 1/2. Consequently, the angles x corresponding to these values within the interval [0, 360] are x = 90°, 270° for Z = 0 and x = 60°, 300° for Z = 1/2.

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Spruance
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Dear all,
How to solve this trigonometric equation systematically?
2cos^(2) x - cos x = 0, where x ∈ [0,360]

Thanks in advance
 
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You can find roots of f(y)=0 when f is any quadratic expression, and given that cos(t)=Z you can find all possible t, so just put those together.
 

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