# Find the principal solutions of cos 2𝑥 = 1 - Mathematics and Statistics

Sum

Find the principal solutions of cos 2𝑥 = 1

#### Solution

cos 2x = 1

∴ cos 2x = cos (0) and cos 2x = cos (2π – 0) = cos 2π

such that 0 ≤ 0 < 2π and 0 ≤ π < 2π

∴ The required principal solutions are x = 0 and x = π.

Concept: Trigonometric Equations and Their Solutions
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