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Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Not the one you use?Change textbook
Chapter 2, Problem 53

In Exercises 39–54, find the exact value of each expression, if possible. Do not use a calculator. sin(sin⁻¹ π)

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Recognize that the expression is \( \sin(\sin^{-1} \pi) \). The function \( \sin^{-1} \) (also called arcsin) is the inverse sine function, which returns an angle whose sine is the given value.
Recall the domain and range of the inverse sine function: \( \sin^{-1} x \) is defined only for \( x \) in the interval \( [-1, 1] \), and it returns an angle \( \theta \) in the range \( [-\frac{\pi}{2}, \frac{\pi}{2}] \).
Since \( \pi \approx 3.14159 \) is outside the domain \( [-1, 1] \) of \( \sin^{-1} \), the expression \( \sin^{-1} \pi \) is not defined in the real numbers.
Therefore, the expression \( \sin(\sin^{-1} \pi) \) cannot be evaluated as a real number because \( \sin^{-1} \pi \) does not exist in the real domain.
Conclude that the exact value of \( \sin(\sin^{-1} \pi) \) is undefined or does not exist in the real number system.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Inverse Sine Function (sin⁻¹ or arcsin)

The inverse sine function, denoted sin⁻¹ or arcsin, returns the angle whose sine is a given number. Its output range is limited to [-π/2, π/2], meaning it only accepts inputs between -1 and 1 for real values.
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Inverse Sine

Domain Restrictions of the Sine Function

The sine function outputs values between -1 and 1, so its inverse function sin⁻¹ only accepts inputs within this range. If the input to sin⁻¹ is outside [-1, 1], the expression is undefined in the real number system.
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Evaluating Composite Trigonometric Expressions

When evaluating expressions like sin(sin⁻¹ x), if x is within the domain of sin⁻¹, the result simplifies to x. However, if x is outside the domain, the expression cannot be evaluated without extending to complex numbers.
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