Table of contents
- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
- 8. Definite Integrals4h 44m
- 9. Graphical Applications of Integrals2h 27m
- 10. Physics Applications of Integrals 2h 22m
3. Techniques of Differentiation
Derivatives of Trig Functions
Problem 3.5.47
Textbook Question
Find the derivative of the following functions.
y = cot x / (1 + csc x)

1
Step 1: Identify the functions involved. The given function is \( y = \frac{\cot x}{1 + \csc x} \). This is a quotient of two functions: the numerator \( u = \cot x \) and the denominator \( v = 1 + \csc x \).
Step 2: Apply the Quotient Rule for derivatives. The Quotient Rule states that if \( y = \frac{u}{v} \), then \( y' = \frac{u'v - uv'}{v^2} \).
Step 3: Find the derivative of the numerator \( u = \cot x \). The derivative \( u' = -\csc^2 x \).
Step 4: Find the derivative of the denominator \( v = 1 + \csc x \). The derivative \( v' = -\csc x \cot x \).
Step 5: Substitute \( u' \), \( v \), \( u \), and \( v' \) into the Quotient Rule formula: \( y' = \frac{(-\csc^2 x)(1 + \csc x) - (\cot x)(-\csc x \cot x)}{(1 + \csc x)^2} \). Simplify the expression to find the derivative.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Derivative
The derivative of a function measures how the function's output value changes as its input value changes. It is a fundamental concept in calculus, representing the slope of the tangent line to the curve of the function at any given point. The derivative is denoted as f'(x) or dy/dx and can be calculated using various rules, such as the product rule, quotient rule, and chain rule.
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Quotient Rule
The quotient rule is a formula used to find the derivative of a function that is the ratio of two other functions. If you have a function y = u/v, where u and v are both differentiable functions of x, the derivative is given by y' = (v * u' - u * v') / v^2. This rule is essential for differentiating functions like the one in the question, where cot x is divided by (1 + csc x).
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Trigonometric Functions and Their Derivatives
Trigonometric functions such as cotangent (cot) and cosecant (csc) have specific derivatives that are crucial for solving problems involving these functions. The derivative of cot x is -csc^2 x, and the derivative of csc x is -csc x * cot x. Understanding these derivatives allows for the effective application of the quotient rule and the overall differentiation process in the given function.
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Introduction to Trigonometric Functions
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