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 3.5.32
Textbook Question
23–51. Calculating derivatives Find the derivative of the following functions.
y = a sin x + b cos x/a sin x - b cos x; a and b are nonzero constants

1
Step 1: Identify the function for which you need to find the derivative. The function given is \( y = \frac{a \sin x + b \cos x}{a \sin x - b \cos x} \).
Step 2: Recognize that this is a quotient of two functions, so you will need to use the Quotient Rule for differentiation. The Quotient Rule states that if you have a function \( y = \frac{u(x)}{v(x)} \), then the derivative \( y' \) is given by \( y' = \frac{u'(x)v(x) - u(x)v'(x)}{(v(x))^2} \).
Step 3: Identify \( u(x) = a \sin x + b \cos x \) and \( v(x) = a \sin x - b \cos x \). Compute the derivatives \( u'(x) \) and \( v'(x) \). Use the derivatives of sine and cosine: \( \frac{d}{dx}(\sin x) = \cos x \) and \( \frac{d}{dx}(\cos x) = -\sin x \).
Step 4: Calculate \( u'(x) = a \cos x - b \sin x \) and \( v'(x) = a \cos x + b \sin x \).
Step 5: Substitute \( u(x) \), \( v(x) \), \( u'(x) \), and \( v'(x) \) into the Quotient Rule formula to find the derivative of \( y \). Simplify the expression if possible.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Derivatives
A derivative represents the rate of change of a function with respect to its variable. It is a fundamental concept in calculus that allows us to determine how a function behaves at any given point. The derivative can be computed using various rules, such as the power rule, product rule, and quotient rule, depending on the form of the function.
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Trigonometric Functions
Trigonometric functions, such as sine and cosine, are periodic functions that relate angles to ratios of sides in right triangles. In calculus, these functions are essential for modeling oscillatory behavior and are frequently encountered in problems involving derivatives. Understanding their properties, such as their derivatives, is crucial for solving calculus problems involving these functions.
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Quotient Rule
The quotient rule is a method for finding the derivative of a function that is the ratio of two other functions. It states that if you have a function y = u/v, where u and v are both differentiable functions, the derivative is given by (v * u' - u * v') / v^2. This rule is particularly useful when differentiating functions like the one in the question, where the function is expressed as a fraction.
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