Chapter 1: Problem 29
Graph \(y=\sin x\) and \(y=\lfloor\sin x\rfloor\) together. What are the domain and range of \(\lfloor\sin x\rfloor ?\)
Short Answer
Expert verified
Domain: all real numbers. Range: \{-1, 0\}.
Step by step solution
01
Understand the Function \(y = \sin x\)
The function \(y = \sin x\) is the sine function, which is a periodic trigonometric function. Its values oscillate between -1 and 1 in a wave-like manner. The domain of this function is all real numbers, meaning \(x \in \mathbb{R}\), because sine is defined for all real numbers. The range is between -1 and 1, inclusive, since those are the minimum and maximum values of the sine function.
02
Understand the Floor Function \(y = \lfloor \sin x \rfloor\)
The floor function, \(y = \lfloor \sin x \rfloor\), takes the value of \(\sin x\) and rounds it down to the nearest integer. So for any given real number \(x\), \(\lfloor \sin x \rfloor\) will be the greatest integer less than or equal to \(\sin x\). Given that \(\sin x\) ranges from -1 to 1, \(\lfloor \sin x \rfloor\) will take integer values.
03
Graph \(y = \sin x\) and \(y = \lfloor \sin x \rfloor\)
Start by graphing the function \(y = \sin x\). Then, use the floor function to plot \(y = \lfloor \sin x \rfloor\). Notice that for ranges where \(\sin x\) is between 0 and 1, \(\lfloor \sin x \rfloor\) is 0. When \(\sin x\) is between -1 and 0, \(\lfloor \sin x \rfloor\) is -1. This pattern repeats as \(\sin x\) oscillates.
04
Determine the Domain of \(\lfloor \sin x \rfloor\)
The domain of \(\lfloor \sin x \rfloor\) is the same as the domain of \(\sin x\), which is all real numbers \(x \in \mathbb{R}\). This is because the floor function does not restrict the input values of \(x\).
05
Determine the Range of \(\lfloor \sin x \rfloor\)
The range of \(\lfloor \sin x \rfloor\) consists of the integer values that \(\lfloor \sin x \rfloor\) can take. As previously explained, since \(\sin x\) fluctuates between and includes -1 and 1, \(\lfloor \sin x \rfloor\) will take values -1, 0, and every point in between creates the integer steps.
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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, represented as \(y = \sin x\), is one of the most familiar trigonometric functions. Think of it as modeling wave-like oscillations or cycles. Here’s what you need to know to understand this function clearly.
- Domain: This function accepts and makes sense of any real number. Thus, the domain is all real numbers, or \(x \in \mathbb{R}\).
- Range: The range is the set of possible output values, which in this case is bounded between -1 and 1, inclusive. This is because the sine of any angle can never be less than -1 or more than 1.
Floor Function
The floor function, denoted \(y = \lfloor x \rfloor\), might seem a bit like magic in mathematics. It rounds down any real number to the nearest integer, and here's how it relates to the sine function.
- Definition: For any real number, \(\lfloor x \rfloor\) represents the greatest integer less than or equal to \(x\).
- Domain & Range: Applied to \(\sin x\), the domain remains \(x \in \mathbb{R}\), as the sine function is defined for all real inputs. Importantly, it translates sine's continuous wave into distinct steps of integer values. Thus, while \(\sin x\) varies smoothly, \(\lfloor \sin x \rfloor\) can only be -1 or 0 within one sine wave cycle.
Graphing Functions
Graphing functions involves picturing their behavior on a coordinate plane, making analysis and comparisons much clearer.To graph \(y = \sin x\), plot a smooth curve that oscillates between -1 and 1, with peaks at \(\frac{\pi}{2}, \frac{5\pi}{2}, \ldots\) and troughs at \(\frac{3\pi}{2}, \frac{7\pi}{2}, \ldots\).- For the floor function \(y = \lfloor \sin x \rfloor\), the graph appears as horizontal steps instead of a curve.
- Segment 0 to 1: In these intervals, \(\lfloor \sin x \rfloor\) is 0, remaining just below the sine curve.
- Segment -1 to 0: Here, \(\lfloor \sin x \rfloor\) steps to -1.