OpenStax, Algebra and Trigonometry 2e §9.5 Solving Trigonometric Equations · Example 15 · Trigonometry · Identities

Solving the Equation Using a Double-Angle Formula

Solve the equation exactly using a double-angle formula: $cos (2 θ) = cos θ .$

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OpenStax, Algebra and Trigonometry 2e · §9.5 Solving Trigonometric Equations · Example 15

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