Trigonometric Identities

Definition: In the unit circle, for any angle $θ$ , the coordinates are $(x, y) = (cos θ, sin θ)$ .
Unit Circle Equation: The equation of the unit circle is $x^{2} + y^{2} = 1$ .
Substitution: Replacing $x$ and $y$ gives $cos^{2} θ + sin^{2} θ = 1$ .
Conclusion: This is the fundamental identity valid for all real and complex values of $θ$ .

This easy difficulty mathematics question is from the chapter trigonometry, covering the topic of trigonometric identities. It appeared in the 2025 exam.

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Trigonometric Identities

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