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Ch. 3 - Trigonometric Identities and Equations
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Non è quello che usi tu?Cambia libro di testo
Capitolo 3, Problema 11

Verify each identity. csc θ - sin θ = cot θ cos θ

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Start by writing down the given identity to verify: \(\csc \theta - \sin \theta = \cot \theta \cos \theta\).
Recall the fundamental trigonometric definitions: \(\csc \theta = \frac{1}{\sin \theta}\) and \(\cot \theta = \frac{\cos \theta}{\sin \theta}\).
Rewrite the left-hand side (LHS) using the definition of cosecant: \(\csc \theta - \sin \theta = \frac{1}{\sin \theta} - \sin \theta\).
Find a common denominator on the LHS to combine the terms: \(\frac{1}{\sin \theta} - \sin \theta = \frac{1 - \sin^2 \theta}{\sin \theta}\).
Use the Pythagorean identity \(1 - \sin^2 \theta = \cos^2 \theta\) to simplify the numerator, so the LHS becomes \(\frac{\cos^2 \theta}{\sin \theta}\). Then compare this with the right-hand side (RHS) \(\cot \theta \cos \theta = \frac{\cos \theta}{\sin \theta} \times \cos \theta = \frac{\cos^2 \theta}{\sin \theta}\) to verify the identity.

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