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
The Chain Rule
Problem 3.17
Textbook Question
Find the derivatives of the functions in Exercises 1–42.
______
𝓻 = √2θ sinθ

1
Identify the function given: \( r = \sqrt{2\theta} \sin\theta \). This is a product of two functions: \( \sqrt{2\theta} \) and \( \sin\theta \).
Apply the product rule for differentiation, which states that if you have a function \( u(\theta) \cdot v(\theta) \), its derivative is \( u'(\theta) \cdot v(\theta) + u(\theta) \cdot v'(\theta) \).
Differentiate \( u(\theta) = \sqrt{2\theta} \). Use the chain rule: \( u'(\theta) = \frac{d}{d\theta}(2\theta)^{1/2} = \frac{1}{2}(2\theta)^{-1/2} \cdot 2 = \frac{1}{\sqrt{2\theta}} \).
Differentiate \( v(\theta) = \sin\theta \). The derivative is \( v'(\theta) = \cos\theta \).
Substitute the derivatives back into the product rule: \( r'(\theta) = \left(\frac{1}{\sqrt{2\theta}}\right) \sin\theta + \sqrt{2\theta} \cos\theta \). Simplify if necessary.

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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 at which a function changes at any given point. It is a fundamental concept in calculus that measures how a function's output value changes as its input value changes. The derivative can be interpreted as the slope of the tangent line to the curve of the function at a specific point.
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Chain Rule
The chain rule is a formula for computing the derivative of a composite function. If a function is composed of two or more functions, the chain rule allows us to differentiate it by multiplying the derivative of the outer function by the derivative of the inner function. This is particularly useful when dealing with functions expressed in terms of other variables, such as polar coordinates.
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Polar Coordinates
Polar coordinates represent points in a plane using a distance from a reference point and an angle from a reference direction. In this context, the function 𝓻 = √2θ sinθ is expressed in polar form, where 𝓻 is the radius and θ is the angle. Understanding how to differentiate functions in polar coordinates is essential for finding derivatives in this format.
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