Problem 49 - Precalculus: Functions and Graphs

Question

Refer to the graph of \(y=\tan x\) to find the exact values of \(x\) In the interval \((-\pi / 2,3 \pi / 2)\) that satisfy the equation. $$\tan x=0$$

Step-by-Step Solution

Answer

The x-values are 0 and \(\pi\).

Step 1: Understand the properties of the tangent function

The tangent function, \(y = \tan x\), crosses the x-axis (where \(\tan x = 0\)) at integer multiples of \(\pi\). This is because \(\tan x = \frac{\sin x}{\cos x}\) and it's zero when \(\sin x = 0\) while \(\cos x eq 0\).

Step 2: Identify the possible x-values in the given interval

The interval \((-\pi / 2, 3\pi / 2)\) can be considered in terms of multiples of \(\pi\): from \(-\pi / 2\) to \(\pi\) and from \(\pi\) to \(3\pi / 2\). The potential x-values are those at which \(\tan x = 0\), occurring at multiples of \(\pi\): \(x = 0\), \(x = \pi\).

Step 3: Verify the exact x-values satisfy the condition

Check that the x-values \(x = 0\) and \(x = \pi\) fall within the specified interval and both satisfy \(\tan x = 0\). For \(x = 0\), \(\tan 0 = 0\). For \(x = \pi\), \(\tan \pi = 0\). Both values satisfy the equation \(\tan x = 0\) and are in the interval.

Key Concepts

Trigonometric Functions

The tangent function, denoted as \( y = \tan x \), is one of the fundamental trigonometric functions used to relate angles to ratios of two sides of a right triangle. Unlike sine or cosine, the tangent function has an interesting property where it creates a vertical asymptote and is undefined wherever \( \cos x = 0 \). This leads to periodic behavior with a vertical period of \( \pi \), meaning the pattern of the graph repeats every \( \pi \) units along the \( x \)-axis.

Key characteristics of the tangent function include:

• The function is undefined at odd integer multiples of \( \pi/2 \), such as \( x = \pm \pi/2, \pm 3\pi/2, ... \).
• Zeros of the function occur at integer multiples of \( \pi \), such as \( x = 0, \pm \pi, \pm 2\pi, ... \).
• The tangent graph goes through the origin \( (0,0) \) and has a basic shape that looks like a series of repeated \( S \)-curves.

Understanding the properties of \( \tan x \) is essential when analyzing its graph or solving equations involving the function. This understanding helps in predicting where the function will be zero, undefined, or in any specific range.

Graph Analysis

When examining the graph of \( y = \tan x \), you're looking at a function that continuously oscillates and is full of useful patterns. Graph analysis involves identifying crucial characteristics like intercepts, asymptotes, and periodicity.

As part of this analysis, notice the following:

• The graph crosses the \( x \)-axis at integer multiples of \( \pi \), which is why the solution to \( \tan x = 0 \) involves finding those \( x \) points.
• Vertical asymptotes occur at odd multiples of \( \pi/2 \), leading to undefined values for \( y \) in these places.
• The function is symmetric around the origin, showing that this is an odd function, meaning \( \tan(-x) = -\tan(x) \).

These patterns are crucial in calculus and precalculus when you need to solve problems involving the tangent function by either sketching its graph or identifying values within a particular interval. It is helpful to visualize these graphs with technology tools to see these patterns more readily and to practice graph recognition skills.

Precalculus Concepts

Precalculus serves as a foundational course that prepares students for higher-level mathematics such as calculus. In this context, mastering the behavior of the tangent function and solving for values that satisfy specific conditions requires a strong grasp of precalculus concepts.

When approaching problems involving \( \tan x \):

• Recognize the periodic nature of trigonometric functions, understanding how these cycles progress within intervals like \((-\pi/2, 3\pi/2)\).
• Apply the knowledge of unit circle and x-intercepts to determine where specific function values, such as \( \tan x = 0 \), occur.
• Understand the concept of function symmetry, which in the case of tangent implies that if \( x \) is a solution, so is \(-x\), but adjusted within the context of its period.

By building these conceptual understandings, students gain the ability to tackle a variety of problems not just limited to tangent functions, but extending to sine, cosine, and their applications in real-world contexts. This lays groundwork for successfully transitioning into calculus and other advanced mathematical analyses.