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 3h 16m
- 11. Integrals of Inverse, Exponential, & Logarithmic Functions2h 34m
6. Derivatives of Inverse, Exponential, & Logarithmic Functions
Derivatives of Inverse Trigonometric Functions
Problem 3.10.42
Textbook Question
Tangent lines Find an equation of the line tangent to the graph of f at the given point.
f(x) = sin−1(x/4); (2,π/6)

1
First, understand that the problem is asking for the equation of the tangent line to the function f(x) = sin^(-1)(x/4) at the point (2, π/6). The tangent line will have the form y = mx + b, where m is the slope and b is the y-intercept.
To find the slope of the tangent line, we need to calculate the derivative of f(x) = sin^(-1)(x/4). The derivative of sin^(-1)(u) with respect to x is 1/√(1-u^2) * du/dx. Here, u = x/4, so du/dx = 1/4.
Substitute u = x/4 into the derivative formula: f'(x) = 1/√(1-(x/4)^2) * (1/4). This gives us the expression for the derivative of f(x).
Evaluate the derivative at the point x = 2 to find the slope of the tangent line. Substitute x = 2 into f'(x) to get the slope m.
Once you have the slope m, use the point-slope form of the equation of a line, y - y1 = m(x - x1), where (x1, y1) is the point (2, π/6). Substitute m, x1 = 2, and y1 = π/6 into this equation to find the equation of the tangent line.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Tangent Line
A tangent line to a curve at a given point is a straight line that touches the curve at that point without crossing it. The slope of the tangent line represents the instantaneous rate of change of the function at that point, which is determined by the derivative of the function.
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Derivative
The derivative of a function at a point quantifies how the function's output changes as its input changes. It is calculated as the limit of the average rate of change of the function over an interval as the interval approaches zero. For the function f(x) = sin⁻¹(x/4), the derivative will help find the slope of the tangent line at the specified point.
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Derivatives
Inverse Trigonometric Functions
Inverse trigonometric functions, such as sin⁻¹(x), are used to find angles when given the value of a trigonometric function. In this case, sin⁻¹(x/4) gives the angle whose sine is x/4. Understanding how to differentiate these functions is crucial for finding the derivative needed to determine the slope of the tangent line.
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Derivatives of Other Inverse Trigonometric Functions
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