Be sure that you've familiarized yourself with the second set of formulas presented in this section by working C5βC8 in the Concept and Vocabulary Check. In Exercises 9β22, express each sum or difference as a product. If possible, find this product's exact value. sin 75Β° + sin 15Β°
Ch. 3 - Trigonometric Identities and Equations

Chapter 3, Problem 22
Use one or more of the six sum and difference identities to solve Exercises 13β54. In Exercises 13β24, find the exact value of each expression. tan ( π /3 + π /4 )
Verified step by step guidance1
Identify the given expression: \(\tan\left( \frac{\pi}{3} + \frac{\pi}{4} \right)\).
Recall the tangent sum identity: \(\tan(A + B) = \frac{\tan A + \tan B}{1 - \tan A \tan B}\).
Set \(A = \frac{\pi}{3}\) and \(B = \frac{\pi}{4}\), then substitute into the identity: \(\tan\left( \frac{\pi}{3} + \frac{\pi}{4} \right) = \frac{\tan \frac{\pi}{3} + \tan \frac{\pi}{4}}{1 - \tan \frac{\pi}{3} \tan \frac{\pi}{4}}\).
Find the exact values of \(\tan \frac{\pi}{3}\) and \(\tan \frac{\pi}{4}\) using known special angles: \(\tan \frac{\pi}{3} = \sqrt{3}\) and \(\tan \frac{\pi}{4} = 1\).
Substitute these values back into the formula and simplify the numerator and denominator separately to express the exact value of the tangent.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Sum and Difference Identities for Tangent
These identities express the tangent of a sum or difference of two angles in terms of the tangents of the individual angles. Specifically, tan(A Β± B) = (tan A Β± tan B) / (1 β tan A tan B). They are essential for breaking down complex angle expressions into simpler parts to find exact values.
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Sum and Difference of Tangent
Exact Values of Trigonometric Functions at Special Angles
Certain angles like Ο/3 and Ο/4 have well-known exact trigonometric values (e.g., tan(Ο/3) = β3, tan(Ο/4) = 1). Knowing these values allows for precise calculation without approximations, which is crucial when applying sum and difference identities to find exact results.
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Introduction to Trigonometric Functions
Simplification of Rational Expressions
After applying the sum or difference identity, the resulting expression often involves fractions and radicals. Simplifying these rational expressions correctly is necessary to arrive at the exact value in its simplest form, ensuring clarity and correctness in the final answer.
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Rationalizing Denominators
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