37. Plutonium-239 The half-life of the plutonium isotope is 24,360 years. If 10 g of plutonium is released into the atmosphere by a nuclear accident, how many years will it take for 80% of the isotope to decay?
Ch. 7 - Transcendental Functions
Chapter 7, Problem 7.6.132
132. What is special about the functions
f(x) = arcsin((1/√(x²+1)) and g(x)=arctan(1/x)?
Explain.
Verified step by step guidance1
First, write down the given functions clearly: \(f(x) = \arcsin\left(\frac{1}{\sqrt{x^{2} + 1}}\right)\) and \(g(x) = \arctan\left(\frac{1}{x}\right)\).
Recall the definitions and ranges of the inverse trigonometric functions \(\arcsin\) and \(\arctan\), and consider how their arguments relate to each other.
Try to express both functions in terms of a common angle or variable by using trigonometric identities. For example, consider setting \(\theta = \arctan(x)\) and rewrite the expressions inside \(f(x)\) and \(g(x)\) in terms of \(\theta\).
Use the Pythagorean identity \(1 + \tan^{2}(\theta) = \sec^{2}(\theta)\) to simplify the expressions inside the inverse functions and see if \(f(x)\) and \(g(x)\) can be related or shown to be equal up to a constant.
Conclude by explaining that the two functions are essentially complementary angles or differ by a constant, highlighting the special relationship between \(f(x)\) and \(g(x)\).

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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 arcsin and arctan reverse the process of sine and tangent, returning an angle given a ratio. Understanding their domains and ranges is essential, as these functions are defined to produce principal values within specific intervals.
Recommended video:
Derivatives of Other Inverse Trigonometric Functions
Function Equivalence and Simplification
Determining if two functions are equivalent often involves algebraic manipulation and trigonometric identities. Simplifying expressions like arcsin(1/√(x²+1)) and arctan(1/x) can reveal hidden relationships or show that they represent the same angle under certain conditions.
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Properties of Functions
Relationship Between Arcsin and Arctan
Arcsin and arctan are related through right triangle definitions and trigonometric identities. For example, arcsin(1/√(x²+1)) can be expressed as arctan(1/x) by considering a triangle with sides x, 1, and √(x²+1), linking these inverse functions geometrically.
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Finding Area Between Curves on a Given Interval
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