/*! 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 39 Simplify the expression. $$\fr... [FREE SOLUTION] | 91Ó°ÊÓ

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Simplify the expression. $$\frac{\sin ^{3} \theta+\cos ^{3} \theta}{\sin \theta+\cos \theta}$$

Short Answer

Expert verified
The expression simplifies to \(1 - \sin \theta \cos \theta\).

Step by step solution

01

Identify the Components

Notice that the expression \(\frac{\sin^3 \theta + \cos^3 \theta}{\sin \theta + \cos \theta}\) seems to match a known algebraic identity for the sum of cubes.
02

Apply Sum of Cubes Formula

Recall the sum of cubes identity: \(a^3 + b^3 = (a + b)(a^2 - ab + b^2)\). In this case, let \(a = \sin \theta\) and \(b = \cos \theta\). So we get:\[\sin^3 \theta + \cos^3 \theta = (\sin \theta + \cos \theta)(\sin^2 \theta - \sin \theta \cos \theta + \cos^2 \theta)\].
03

Simplify Using Trigonometric Identity

Substitute the trigonometric identity \(\sin^2 \theta + \cos^2 \theta = 1\) into the expression. Therefore, the expression \(\sin^2 \theta - \sin \theta \cos \theta + \cos^2 \theta\) simplifies to:\[1 - \sin \theta \cos \theta\].
04

Cancel Out Common Factors

Since \(\sin \theta + \cos \theta\) is a factor in both the numerator and denominator, it can be cancelled out. Therefore, the simplified expression is \(1 - \sin \theta \cos \theta\).
05

Final Expression

Thus, the expression simplifies to \(1 - \sin \theta \cos \theta\).

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Key Concepts

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

Understanding the Sum of Cubes
When approaching algebraic expressions, recognizing patterns, like the sum of cubes, can ease the simplification process. The sum of cubes is a particular identity used often in algebra and trigonometry. The formula for the sum of cubes is:
  • \(a^3 + b^3 = (a + b)(a^2 - ab + b^2)\)
Here, the expression is split into two simpler expressions: one involving the sum \((a + b)\) and another with a mixture of squares and cross products \((a^2 - ab + b^2)\).
In the given exercise, this identity helps in breaking down complex trigonometric powers into more manageable parts. By substituting, \(a = \sin \theta\) and \(b = \cos \theta\), we can directly apply this identity and transform the given expression into a product of factors. Leveraging such identities can make mathematical expressions simpler and more comprehensible.
The Art of Simplification
Simplification in mathematics, especially in dealing with complex trigonometric identities, is key to finding a clearer expression. Simplifying expressions involves reducing them to their simplest form. It is done by identifying and canceling common terms or using known identities.
For the initial expression, recognizing that \(\sin^2 \theta + \cos^2 \theta = 1\) is crucial. This identity allows the trigonometric components inside the expression to be consolidated into simpler forms.
  • Replace \(\sin^2 \theta + \cos^2 \theta\) with 1.
  • Focus on reducing the cross products.
  • Cancel similar terms in the numerator and denominator.
By performing these distinct steps, you derive a less complex result, improving both the understanding and efficiency of handling the expression.
Grasping Algebraic Identity
Algebraic identities are innate tools to verify or simplify algebraic equations. These are equations true for all values of their variables. For trigonometric expressions, like the one in our exercise, such identities play an integral role in reconfiguring and simplifying terms.
  • The sum of cubes itself is an algebraic identity that aids in disassembling and then reconstructing expressions into solvable components.
  • Understanding these recurrent patterns allows for the cancelation of common factors efficiently.
These identities act as familiar templates that can simplify problem-solving strategies. By recognizing specific patterns in trigonometric problems, students can apply these identities to streamline their calculations, leading to more straightforward solutions and a deeper understanding of trigonometric functions.

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Most popular questions from this chapter

Trigonometric functions are used extensively in the design of industrial robots. Suppose that a robot's shoulder joint is motorized so that the angle \(\theta\) increases at a constant rate of \(\pi / 12\) radian per second from an initial angle of \(\theta=0\). Assume that the elbow joint is always kept straight and that the arm has a constant length of 153 centimeters, as shown in the figure. (a) Assume that \(h=50 \mathrm{~cm}\) when \(\theta=0\). Construct a table that lists the angle \(\theta\) and the height \(h\) of the robotic hand every second while \(0 \leq \theta \leq \pi / 2\). (b) Determine whether or not a constant increase in the angle \(\theta\) produces a constant increase in the height of the hand. (c) Find the total distance that the hand moves.

The tallest man-made structure in the world is a television transmitting tower located near Mayville, North Dakota. From a distance of 1 mile on level ground, its angle of elevation is \(21^{\circ} 20^{\prime} 24^{\prime \prime}\). Determine its height to the nearest foot.

Rewrite the expression in nonradical form without using absolute values for the indicated values of \(\theta\). $$\sqrt{\sin ^{2}(\theta / 2)}, \quad 2 \pi<\theta<4 \pi$$

A ship leaves port at 1:00 P.M. and sails in the direction \(\mathrm{N} 34^{\circ} \mathrm{W}\) at a rate of \(24 \mathrm{mi} / \mathrm{hr}\). Another ship leaves port at 1:30 P.M. and sails in the direction \(\mathrm{N} 56^{\circ} \mathrm{E}\) at a rate of \(18 \mathrm{mi} / \mathrm{hr}\). (a) Approximately how far apart are the ships at 3:00 P.M.? (b) What is the bearing, to the nearest degree, from the first ship to the second?

Exer. 9-16: Let \(P\) be the point on the unit circle \(U\) that corresponds to \(t\). Find the coordinates of \(P\) and the exact values of the trigonometric functions of \(t\), whenever possible. (a) \(5 \pi / 2\) (b) \(-\pi / 2\)

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