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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 3.2.61c

In Exercises 57–64, find the exact value of the following under the given conditions:
c. tan (α + β)
cos α = 8/17, α lies in quadrant IV, and sin β = -1/2, β lies in quadrant III.

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Identify the given information: \(\cos \alpha = \frac{8}{17}\) with \(\alpha\) in quadrant IV, and \(\sin \beta = -\frac{1}{2}\) with \(\beta\) in quadrant III.
Determine the signs and values of \(\sin \alpha\) and \(\cos \beta\) using the Pythagorean identity \(\sin^2 \theta + \cos^2 \theta = 1\), considering the quadrant of each angle.
Calculate \(\sin \alpha\) by using \(\sin \alpha = -\sqrt{1 - \cos^2 \alpha}\) since \(\alpha\) is in quadrant IV where sine is negative.
Calculate \(\cos \beta\) by using \(\cos \beta = -\sqrt{1 - \sin^2 \beta}\) since \(\beta\) is in quadrant III where cosine is negative.
Use the angle addition formula for tangent: \(\tan(\alpha + \beta) = \frac{\tan \alpha + \tan \beta}{1 - \tan \alpha \tan \beta}\), where \(\tan \alpha = \frac{\sin \alpha}{\cos \alpha}\) and \(\tan \beta = \frac{\sin \beta}{\cos \beta}\). Substitute the values found to express \(\tan(\alpha + \beta)\).

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