Chapter 7: Problem 17
Find \(\sin \theta\) $$\csc \theta=-\frac{2}{4}$$
Short Answer
Expert verified
The value of \(\text{sin} \theta\) is \(-2\).
Step by step solution
01
Simplify \(\frac{-2}{4}\)
The given \(\frac{-2}{4}\) can be simplified by dividing both the numerator and the denominator by their greatest common divisor. \(\frac{-2}{4} = \frac{-1}{2}\).
02
Recall the relationship between \(\text{csc} \theta\) and \(\text{sin} \theta\)
The cosecant function is the reciprocal of the sine function. Therefore, \(\text{csc} \theta = \frac{1}{\text{sin} \theta}\). Given that \(\text{csc} \theta = \frac{-1}{2}\), it follows that \(\text{sin} \theta = \frac{1}{\text{csc} \theta}\).
03
Evaluate \(\text{sin} \theta\)
Now substitute the given value for \(\text{csc} \theta\): \(\text{sin} \theta = \frac{1}{\frac{-1}{2}} = -2\).
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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, often written as \(\text{sin} \theta\), is a fundamental trigonometric function that describes the relationship between the angle of a right triangle and the ratio of the length of the side opposite the angle to the length of the hypotenuse. Simply put, if you have a right triangle:
- One of its angles, labeled \(\theta\), will guide you in determining specific side lengths.
- The side opposite this angle is called the **opposite side**.
- The longest side, opposite the right angle, is the **hypotenuse**.
cosecant function
The cosecant function, denoted as \(\text{csc} \theta\), is the reciprocal of the sine function. This means it is the inverse of the sine function with respect to multiplication. Therefore, \(\text{csc} \theta\) is defined as: \(\text{csc} \theta = \frac{1}{\text{sin} \theta}\). Because it is a reciprocal, if the sine of \(\theta\) is known, the cosecant can be easily calculated. In practical terms:
- When \(\text{sin} \theta\) is small, \(\text{csc} \theta\) can become large.
- Conversely, when \(\text{sin} \theta\) is large, \(\text{csc} \theta\) can be small.
- Keep in mind, \(\text{csc} \theta\) is undefined when \(\text{sin} \theta = 0\) because division by zero is undefined.
reciprocal relationships
Reciprocal relationships are a key concept in understanding trigonometric functions. A reciprocal of a number is essentially its 'flip.' For example, the reciprocal of 2 is \(\frac{1}{2}\), and the reciprocal of -\frac{1}{2} is -2. In trigonometry, this principle is employed extensively:
- The sine function \(\text{sin} \theta\) and the cosecant function \(\text{csc} \theta\) are reciprocals of each other. So, \(\text{csc} \theta = \frac{1}{\text{sin} \theta}\) and \(\text{sin} \theta = \frac{1}{\text{csc} \theta}\).
- Similarly, other trigonometric pairs like cosine \(\text{cos} \theta\) and secant \(\text{sec} \theta\), and tangent \(\text{tan} \theta\) and cotangent \(\text{cot} \theta\), follow this reciprocal relationship.
- We began with \(\text{csc} \theta = -\frac{1}{2}\).
- By applying the reciprocal relationship, we found \(\text{sin} \theta = -2\).