Chapter 6: Problem 44
Verify the Identity. $$\frac{\csc (-t)-\sin (-t)}{\sin (-t)}=\cot ^{2} t$$
Short Answer
Expert verified
The identity \( \frac{\csc (-t)-\sin (-t)}{\sin (-t)}=\cot ^{2} t \) is verified.
Step by step solution
01
Simplify Trigonometric Functions
First, we note the identity for the cosecant and sine of negative angles: \( \csc(-t) = \frac{1}{\sin(-t)} \) and \( \sin(-t) = -\sin(t) \). Thus, the given expression becomes \( \frac{\frac{1}{-\sin(t)} + \sin(t)}{-\sin(t)} \). Simplifying this gives us \( \frac{-\frac{1}{\sin(t)} - \sin(t)}{-\sin(t)} \).
02
Simplify the Fraction
Let's simplify the expression \( \frac{-\frac{1}{\sin(t)} - \sin(t)}{-\sin(t)} \). Combine the terms in the numerator to obtain a single fraction: \( \frac{-1 - \sin^2(t)}{-\sin(t)} \).
03
Simplify Negative Signs
Factor out the negative sign from the numerator: \( \frac{-1 - \sin^2(t)}{-\sin(t)} = \frac{-(1 + \sin^2(t))}{-\sin(t)} \). Cancelling the negative signs, we get \( \frac{1 + \sin^2(t)}{\sin(t)} \).
04
Use Pythagorean Identity
Using the Pythagorean identity, \( \sin^2(t) + \cos^2(t) = 1 \), we can substitute for 1 to get \( \cos^2(t) + \sin^2(t) = 1 + \sin^2(t) \). Substituting into our fraction: \( \frac{\cos^2(t)}{\sin(t)} \).
05
Express Result in Terms of Cotangent
Note that \( \cot(t) = \frac{\cos(t)}{\sin(t)} \). Thus, \( \cot^2(t) = \left(\frac{\cos(t)}{\sin(t)}\right)^2 = \frac{\cos^2(t)}{\sin^2(t)} \). Thus, \( \frac{\cos^2(t)}{\sin(t)} = \frac{\cos^2(t)\cdot \sin(t)}{\sin^2(t)} = \cot^2(t) \), verifying the identity.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cosecant Function
The Cosecant function, denoted as \( \csc(t) \), is a trigonometric function that is the reciprocal of the sine function. In simple terms, this means it is the inverse of sine. Therefore, the relationship can be expressed as:
- \( \csc(t) = \frac{1}{\sin(t)} \)
- \( \csc(-t) = \frac{1}{\sin(-t)} \)
Sine Function
The Sine function, represented as \( \sin(t) \), is one of the fundamental trigonometric functions that relates an angle of a right-angled triangle to the ratio of the length of the side opposite the angle to the hypotenuse. For any angle \( t \) in a unit circle, sine can also be interpreted as the y-coordinate of a point on the circle. For negative angles, the sine function holds the identity:
- \( \sin(-t) = -\sin(t) \)
Pythagorean Identity
The Pythagorean Identity is a vital tool in trigonometry, based on the Pythagorean Theorem. It states:
- \( \sin^2(t) + \cos^2(t) = 1 \)