Evaluate the expression.
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
5. Inverse Trigonometric Functions and Basic Trigonometric Equations
Evaluate Composite Trig Functions
Problem 45
Textbook Question
In Exercises 39–54, find the exact value of each expression, if possible. Do not use a calculator. tan (tan⁻¹ 125)
Verified step by step guidance1
Recognize that the expression is \( \tan(\tan^{-1}(125)) \). Here, \( \tan^{-1} \) is the inverse tangent function, also called arctangent, which returns an angle whose tangent is the given number.
Understand that \( \tan^{-1}(125) \) gives an angle \( \theta \) such that \( \tan(\theta) = 125 \).
Since \( \tan \) and \( \tan^{-1} \) are inverse functions, applying \( \tan \) to \( \tan^{-1}(125) \) essentially returns the original input value, provided the angle is within the principal range of \( \tan^{-1} \).
Therefore, the expression simplifies to \( 125 \) because \( \tan(\tan^{-1}(x)) = x \) for all real numbers \( x \).
No further calculation is needed, and the exact value of the expression is \( 125 \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Inverse Trigonometric Functions
Inverse trigonometric functions, like tan⁻¹ (arctan), return the angle whose trigonometric ratio equals a given value. For example, tan⁻¹(125) gives the angle whose tangent is 125. Understanding this helps in simplifying expressions involving inverse functions.
Recommended video:
Introduction to Inverse Trig Functions
Tangent Function and Its Properties
The tangent function relates an angle in a right triangle to the ratio of the opposite side over the adjacent side. It is periodic and defined for all real numbers except odd multiples of 90°. Knowing that tan and tan⁻¹ are inverse functions helps simplify tan(tan⁻¹(x)) to x within the function's domain.
Recommended video:
Introduction to Tangent Graph
Simplification of Composite Functions
When a function and its inverse are composed, such as tan(tan⁻¹(x)), the result simplifies to x, provided x is within the domain of the inverse function. This principle allows direct evaluation of expressions without a calculator by recognizing the cancellation effect.
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Evaluate Composite Functions - Special Cases
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