Chapter 4: Problem 1
Find the angles \(\sin ^{-1} y\) and \(\cos ^{-1} y\) and \(\tan ^{-1} y\) in radians. \(y=0\)
Short Answer
Expert verified
\( \sin^{-1}(0) = 0 \), \( \cos^{-1}(0) = \frac{\pi}{2} \), \( \tan^{-1}(0) = 0 \).
Step by step solution
01
Understanding the Problem
We need to find the angles corresponding to inverse trigonometric functions: \( \sin^{-1}(y) \), \( \cos^{-1}(y) \), and \( \tan^{-1}(y) \) where \( y = 0 \). Each of these functions will return an angle measure in radians.
02
Finding \( \sin^{-1}(0) \)
The function \( \sin^{-1}(x) \) returns the angle \( \theta \) whose sine is \( x \), with \( \theta \) in the range \( [-\frac{\pi}{2}, \frac{\pi}{2}] \). Since \( \sin(0) = 0 \), \( \sin^{-1}(0) = 0 \). So, the angle is \( 0 \) radians.
03
Finding \( \cos^{-1}(0) \)
The function \( \cos^{-1}(x) \) returns the angle \( \theta \) whose cosine is \( x \), with \( \theta \) in the range \( [0, \pi] \). Since \( \cos(\frac{\pi}{2}) = 0 \), \( \cos^{-1}(0) = \frac{\pi}{2} \). So, the angle is \( \frac{\pi}{2} \) radians.
04
Finding \( \tan^{-1}(0) \)
The function \( \tan^{-1}(x) \) returns the angle \( \theta \) whose tangent is \( x \), with \( \theta \) in the range \( (-\frac{\pi}{2}, \frac{\pi}{2}) \). Since \( \tan(0) = 0 \), \( \tan^{-1}(0) = 0 \). So, the angle is \( 0 \) radians.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
arcsin function
The arcsine function, denoted as \( \sin^{-1}(x) \) or \( \arcsin(x) \), is the inverse of the sine function. It allows us to find an angle whose sine value we know. Let's make sense of this with an example. Suppose you have a sine value of 0, and you need to determine what angle corresponds to this value in radians. This is precisely what \( \arcsin(0) \) tells us.
- The answer to \( \arcsin(0) \) is the angle \( \theta \) such that \( \sin(\theta) = 0 \).
- This angle \( \theta \) must lie within the range \([ -\frac{\pi}{2}, \frac{\pi}{2} ]\), which is the principal range for the arcsin function.
- Since \( \sin(0) = 0 \), clearly \( \arcsin(0) = 0 \) radians.
arccos function
The arccosine function, expressed as \( \cos^{-1}(x) \) or \( \arccos(x) \), is used to determine the angle whose cosine value is known. By definition, it helps us reverse the cosine function to find the corresponding angle in its principal range, \([0, \pi]\).
Suppose you're given that \( \cos(\theta) = 0 \). The question is, "What is the angle \( \theta \)?" This is where \( \arccos(0) \) comes into play.
Suppose you're given that \( \cos(\theta) = 0 \). The question is, "What is the angle \( \theta \)?" This is where \( \arccos(0) \) comes into play.
- The principal range for arccos is \([0, \pi]\), meaning it will only give us angles between 0 and \( \pi \) radians.
- Since \( \cos(\frac{\pi}{2}) = 0 \), this means \( \arccos(0) = \frac{\pi}{2} \).
- This unique angle ensures we have a consistent output, making the arccos function predictable and reliable.
arctan function
The arctangent function, commonly written as \( \tan^{-1}(x) \) or \( \arctan(x) \), helps us find the angle whose tangent is a specific number. This process is vital in situations where we know the tangent of an angle and wish to find the angle itself.
Consider the scenario where \( \tan(\theta) = 0 \). Finding \( \theta \) involves determining \( \arctan(0) \), which is simply asking "What angle has a tangent of 0?"
Consider the scenario where \( \tan(\theta) = 0 \). Finding \( \theta \) involves determining \( \arctan(0) \), which is simply asking "What angle has a tangent of 0?"
- The principal range for arctan is \( (-\frac{\pi}{2}, \frac{\pi}{2}) \), indicating that it returns angles within this interval.
- Since \( \tan(0) = 0 \), \( \arctan(0) = 0 \) radians, which falls within the principal range.
- Because it covers all real numbers, it's often used in practical applications like finding angles in right triangles.