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In Exercises \(82-128\), verify the identity. Assume that all quantities are defined. $$ \frac{\sin (\theta)}{\cos ^{2}(\theta)}=\sec (\theta) \tan (\theta) $$

Short Answer

Expert verified
Both sides simplify to \(\frac{\sin(\theta)}{\cos^2(\theta)}\), confirming the identity.

Step by step solution

01

Recall Trigonometric Identities

Recall that the secant and tangent functions are defined as follows: \(\sec(\theta) = \frac{1}{\cos(\theta)}\) and \(\tan(\theta) = \frac{\sin(\theta)}{\cos(\theta)}\). We'll use these definitions to transform the right side of the equation.
02

Simplify Right Side of the Equation

Using the definitions from Step 1, we write the right side as a single expression by applying the identities: \(\sec(\theta) \tan(\theta) = \left(\frac{1}{\cos(\theta)}\right) \left(\frac{\sin(\theta)}{\cos(\theta)}\right) = \frac{\sin(\theta)}{\cos^2(\theta)}\).
03

Compare Both Sides

Now compare the right side, \(\frac{\sin(\theta)}{\cos^2(\theta)}\), with the left side of the equation, \(\frac{\sin(\theta)}{\cos^{2}(\theta)}\). Both sides are equivalent, validating the identity.

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Key Concepts

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

Secant Function
The secant function, often abbreviated as \(\sec(\theta)\), is one of the six fundamental trigonometric functions. It is defined as the reciprocal of the cosine function. That means \(\sec(\theta) = \frac{1}{\cos(\theta)}\). This definition highlights an important relationship between the secant and cosine functions, which can be quite helpful in simplifying trigonometric expressions.
When dealing with identities or expressions involving the secant function, it can be useful to convert \(\sec(\theta)\) into its reciprocal form. Doing so often simplifies the task of verifying trigonometric identities, as evidenced in the way we handle such terms in equations. It also emphasizes the interconnected nature of all trigonometric functions, allowing you to switch from one to the other based on what is easier to manipulate in a given situation.
Tangent Function
The tangent function, or \(\tan(\theta)\), plays a pivotal role in trigonometry, particularly because it relates the sine and cosine functions. It is defined as the ratio of sine to cosine: \(\tan(\theta) = \frac{\sin(\theta)}{\cos(\theta)}\). This formula shows that tangent can be expressed directly through sine and cosine, making it extremely flexible in various algebraic manipulations.
Mentioned often in problems of verifying identities, the tangent function helps bridge gaps between different trigonometric expressions. By expressing \(\tan(\theta)\) using \(\sin(\theta)\) and \(\cos(\theta)\), you can often see immediate cancellations or simplifications in complex identities. Understanding this function not only aids in solving typical trigonometric problems but also enhances your problem-solving toolkit when dealing with real-world applications.
Verify Identity
Verifying trigonometric identities can seem daunting at first, but the process is systematic and logical. It involves showing that two different expressions are indeed equal when reduced to their simplest form. This exercise demonstrated the process effectively: we used fundamental trigonometric definitions and properties to transform one side of the given identity to look exactly like the other side.
  • Understand the Definitions: Start by recalling basic definitions, like \(\tan(\theta)\) and \(\sec(\theta)\). These definitions are the building blocks of verifying any identity.
  • Transform Carefully: Use algebraic manipulation to transform expressions. For the identity \(\frac{\sin(\theta)}{\cos^{2}(\theta)} = \sec(\theta) \tan(\theta)\), we used the definition \(\sec(\theta) \tan(\theta) = \frac{1}{\cos(\theta)} \cdot \frac{\sin(\theta)}{\cos(\theta)}\) to simplify the right side.
  • Make Comparisons: Once both sides of the equation appear identical, the identity is verified. This means your transformations have been applied correctly and the expressions are equivalent.
Practicing such problems improves your ability to recognize patterns and connections between different trigonometric functions, which is crucial for advanced studies in mathematics and engineering.

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Most popular questions from this chapter

A tag-and-release program to study the Sasquatch population of the eponymous Sasquatch National Park is begun. From a 200 foot tall tower, a ranger spots a Sasquatch lumbering through the wilderness directly towards the tower. Let \(\theta\) denote the angle of depression from the top of the tower to a point on the ground. If the range of the rifle with a tranquilizer dart is 300 feet, find the smallest value of \(\theta\) for which the corresponding point on the ground is in range of the rifle. Round your answer to the nearest hundreth of a degree.

At Cliffs of Insanity Point, The Great Sasquatch Canyon is 7117 feet deep. From that point, a fire is seen at a location known to be 10 miles away from the base of the sheer canyon wall. What angle of depression is made by the line of sight from the canyon edge to the fire? Express your answer using degree measure rounded to one decimal place.

A guy wire 1000 feet long is attached to the top of a tower. When pulled taut it touches level ground 360 feet from the base of the tower. What angle does the wire make with the ground? Express your answer using degree measure rounded to one decimal place.

find the exact value or state that it is undefined. \(\csc \left(\arcsin \left(\frac{3}{5}\right)\right)\)

Assume that the range of arcsecant is \(\left[0, \frac{\pi}{2}\right) \cup\left[\pi, \frac{3 \pi}{2}\right)\) and that the range of arccosecant is \(\left(0, \frac{\pi}{2}\right] \cup\left(\pi, \frac{3 \pi}{2}\right]\) when finding the exact value. \(\operatorname{arcsec}\left(\sec \left(\frac{11 \pi}{12}\right)\right)\)

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