/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 113 Solve each problem. A painting... [FREE SOLUTION] | 91Ó°ÊÓ

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Solve each problem. A painting 3 feet high and 6 feet from the floor will cut off an angle $$\theta=\tan ^{-1}\left(\frac{3 x}{x^{2}+4}\right)$$ to an observer. Assume that the observer is \(x\) feet from the wall where the painting is displayed and that the eyes of the observer are 5 feet above the ground. (IMAGE CAN'T COPY). Find the value of \(\theta\) for each value of \(x\) to the nearest degree. (a) \(x=3\) (b) \(x=6\) (c) \(x=9\) (d) Derive the given formula for \(\theta\). (Hint: Use right triangles and the identity for \(\tan (\theta-\alpha) .)\) (e) Graph the function for \(\theta\) with a calculator, and determine the distance that maximizes the angle.

Short Answer

Expert verified
(a) \(\theta \approx 35^\circ\), (b) \(\theta \approx 25^\circ\), (c) \(\theta \approx 18^\circ\); max angle at \( x \approx 3 \).

Step by step solution

01

Calculate \( \theta \) for \( x = 3 \)

Plug \( x = 3 \) into the formula: \[ \theta = \tan^{-1}\left(\frac{3 \times 3}{3^2 + 4}\right) = \tan^{-1}\left(\frac{9}{9 + 4}\right) = \tan^{-1}\left(\frac{9}{13}\right) \]. Use a calculator to find \( \theta \) to the nearest degree: \( \theta \approx 35^\circ \).
02

Calculate \( \theta \) for \( x = 6 \)

Plug \( x = 6 \) into the formula: \[ \theta = \tan^{-1}\left(\frac{3 \times 6}{6^2 + 4}\right) = \tan^{-1}\left(\frac{18}{36 + 4}\right) = \tan^{-1}\left(\frac{18}{40}\right) \]. Use a calculator to find \( \theta \) to the nearest degree: \( \theta \approx 25^\circ \).
03

Calculate \( \theta \) for \( x = 9 \)

Plug \( x = 9 \) into the formula: \[ \theta = \tan^{-1}\left(\frac{3 \times 9}{9^2 + 4}\right) = \tan^{-1}\left(\frac{27}{81 + 4}\right) = \tan^{-1}\left(\frac{27}{85}\right) \]. Use a calculator to find \( \theta \) to the nearest degree: \( \theta \approx 18^\circ \).
04

Derive the formula for \(\theta\)

Utilize the tangent difference identity \( \tan(\theta - \alpha) = \frac{\tan \theta - \tan \alpha}{1 + \tan \theta \tan \alpha} \). Set up the right triangle with height difference 3 feet (painting height minus the observer's eye level): \( \tan \theta = \frac{3}{x} \) and \( \tan \alpha = \frac{5}{x} \). With \( \theta \) as the angle the painting subtends and \( \alpha \) as the observer's angle to the floor, by considering another triangle with base 4 (distance from observer's eyes to floor), derive: \[ \theta = \tan^{-1}\left(\frac{3x}{x^2+4}\right) \].
05

Determine maximum angle using calculator graph

Graph \( \theta = \tan^{-1}\left(\frac{3x}{x^2+4}\right) \) over a reasonable range of \( x \). Using a graphing calculator, find the value of \( x \) where \( \theta \) is maximized by inspecting the function's peak. The maximum typically happens slightly more than the painting height (3 feet) from the wall. Estimate \( x \approx 3 \) feet for the maximum angle.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Tangent function
The tangent function, often abbreviated as "tan," plays a crucial role in trigonometry by relating the angle of a right triangle to its opposite side divided by its adjacent side. In our exercise, we encounter the tangent of an angle, given in a formula involving the position of an observer in relation to a painting. The formula \( \theta = \tan^{-1}\left(\frac{3x}{x^2+4}\right) \) highlights how the tangent inverse or arc tangent function is used to calculate the angle based on the distance from the wall. This application shows how the tangent function helps in practical scenarios like determining viewing angles, crucial for architects or designers considering optimal viewing conditions. Understanding this relationship is essential for solving problems related to angle measurements and distances in trigonometric contexts.
Inverse trigonometric functions
Inverse trigonometric functions are used to determine angles when given trigonometric ratios. In our exercise, the inverse of the tangent function, \( \tan^{-1} \), computes the angle \( \theta \) formed by a painting and an observer. It reverses the process of the tangent function to find angles when given the ratio of two sides.

These inverse functions are key in fields requiring precise angular measurements, like engineering or physics. They enable solutions for scenarios where direct measurement of angles isn't possible. When you use \( \tan^{-1} \) with a calculator, it produces an angle in degrees or radians, depending on settings. Here, it constrains the value of \( \theta \) to the principle range, typically between -90° and 90°, simplifying angle evaluation for practical tasks.
Graphing functions
Graphing functions is a powerful technique to visualize relationships between variables. Our exercise involves plotting \( \theta = \tan^{-1}\left(\frac{3x}{x^2+4}\right) \) to determine where the angle is maximized. By graphing, we turn complex algebraic relationships into a visible form, making it easier to identify trends like peaks or troughs.

This step requires graphing calculators or software, where you input the function and observe the curve's behavior over a range of \( x \) values. A graph helps in spotting the maximum point of \( \theta \), indicating the optimal distance an observer can be from the wall for the best viewing angle of the painting. This visualization supports decision-making by clearly illustrating how the angle changes as one moves further away.
Optimization in trigonometry
Optimization is about finding the best solution within given conditions. In trigonometry, this might mean determining the angle, distance, or configuration that achieves a specific goal. In our problem, optimization involves finding the distance \( x \) where \( \theta \), the viewing angle, is maximized.

By examining our graph of \( \theta = \tan^{-1}\left(\frac{3x}{x^2+4}\right) \), we pinpoint where the angle reaches its peak. The graph reveals this optimal value, giving insights into ideal positions for viewing the painting. Understanding and applying optimization techniques helps tackle real-world challenges where the best possible outcome is needed, such as in architectural designs, ensuring comfort and clarity for observers. This concept extends beyond mathematics into practical applications in various fields.

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