Chapter 4: Problem 84
In Exercises 83-86, assume \(A\) and \(B\) are positive real numbers. $$ \text { Find the } y \text {-intercept of the function } y=A \sin (B x) \text {. } $$
Short Answer
Expert verified
The y-intercept is at the point (0, 0).
Step by step solution
01
Identify the y-intercept location
The y-intercept of a function is the point where the graph of the function crosses the y-axis. This occurs when the input value, \(x\), is equal to 0.
02
Substitute x with 0 in the function
Substitute \(x = 0\) into the function equation \(y = A \sin(Bx)\). This results in \(y = A \sin(B \cdot 0)\).
03
Simplify the expression
Recall that the sine of 0 is 0, i.e., \(\sin(0) = 0\). Substitute this into the equation to get \(y = A \cdot 0 = 0\).
04
State the y-intercept
The y-coordinate of the y-intercept is 0. Therefore, the y-intercept of the function \(y = A \sin(Bx)\) is the point \((0, 0)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Sine Function
The sine function is a fundamental part of trigonometry and plays a crucial role in various mathematical settings, including calculus and physics. The sine function is often represented as \( \sin(x) \) and maps angles, typically measured in radians, to a ratio of side lengths in a right-angled triangle.
The sine function has several key characteristics:
The sine function has several key characteristics:
- It is periodic, which means it repeats its values in regular intervals. For the sine function, this interval, or period, is \( 2\pi \).
- It oscillates between values of -1 and 1. Hence, the range of the sine function is \([-1, 1]\).
- It has a wave-like pattern, often referred to as a sine wave, which can model various real-world phenomena such as sound and light waves.
Real Numbers
Real numbers are a set that includes both rational and irrational numbers. They form the continuous number line used in mathematics. Here are some key points to remember about real numbers:
- They include positive numbers, negative numbers, and zero.
- Examples of real numbers are integers, fractions, and irrational numbers like \(\pi\) and \(\sqrt{2}\).
- In the context of the function \(y = A \sin(Bx)\), both \(A\) and \(B\) are specified as positive real numbers. This means they can take on any positive value on the continuous number line.
- Real numbers are crucial because they allow us to perform calculus and analyze continuous functions and curves, like those of the sine wave.
Graph of Functions
The graph of a function visually represents the relationship between the input values (often represented as \(x\)) and the output values (often represented as \(y\)). The graph of a sine function, such as \(y = A \sin(Bx)\), is an excellent example of this relationship in action.
Several features define the graph of the sine function:
Several features define the graph of the sine function:
- Y-intercept: This is where the graph crosses the y-axis, corresponding to \(x = 0\). For the function \(y = A \sin(Bx)\), as solved, the y-intercept is \((0,0)\).
- Periodicity: The function repeats its values every \(2\pi\) for \(\sin(x)\). However, the coefficient \(B\) in \(y = A \sin(Bx)\) modifies this to \(\frac{2\pi}{B}\).
- Amplitude: This is the maximum distance from the center line to the peak. In our function, the amplitude is \(A\).
- Symmetry: Sine functions are symmetric about the origin, a feature known as odd symmetry, meaning \(\sin(-x) = -\sin(x)\).