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Ch. 1 - Angles and the Trigonometric Functions
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Non è quello che usi tu?Cambia libro di testo
Capitolo 1, Problema 87

In Exercises 87–92, find the exact value of each expression. Write the answer as a single fraction. Do not use a calculator. sin 𝜋/3 cos 𝜋 - cos 𝜋/3 sin 3𝜋/2

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1
Recognize that the expression is of the form \(\sin A \cos B - \cos A \sin B\), which matches the sine difference identity: \(\sin(A - B) = \sin A \cos B - \cos A \sin B\).
Identify the angles in the expression: \(A = \frac{\pi}{3}\) and \(B = \frac{2\pi}{3}\), so the expression simplifies to \(\sin\left(\frac{\pi}{3} - \frac{2\pi}{3}\right)\).
Calculate the difference inside the sine function: \(\frac{\pi}{3} - \frac{2\pi}{3} = -\frac{\pi}{3}\).
Use the odd property of sine: \(\sin(-\theta) = -\sin \theta\), so \(\sin\left(-\frac{\pi}{3}\right) = -\sin\left(\frac{\pi}{3}\right)\).
Recall the exact value of \(\sin\left(\frac{\pi}{3}\right)\), which is \(\frac{\sqrt{3}}{2}\), and write the final expression as a single fraction using this value.

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