Ch. 3 - Derivatives

Briggs - Calculus: Early Transcendentals 3rd Edition

Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook

Briggs 3rd Edition

Ch. 3 - Derivatives

Problem 3.10.11

Chapter 3, Problem 3.10.11

Find the slope of the curve y=sin^-1 x at (1/2, π/6) without calculating the derivative of sin^-1 x.

Verified step by step guidance

Step 1: Recognize that the slope of the curve at a given point is the derivative of the function at that point. Here, we need the derivative of \( y = \sin^{-1}(x) \).

Step 2: Use the identity \( y = \sin^{-1}(x) \) implies \( \sin(y) = x \). Differentiate both sides with respect to \( x \).

Step 3: Apply implicit differentiation. The derivative of \( \sin(y) \) with respect to \( x \) is \( \cos(y) \cdot \frac{dy}{dx} \), and the derivative of \( x \) is 1.

Step 4: Set up the equation from implicit differentiation: \( \cos(y) \cdot \frac{dy}{dx} = 1 \). Solve for \( \frac{dy}{dx} \) to find \( \frac{dy}{dx} = \frac{1}{\cos(y)} \).

Step 5: Evaluate \( \cos(y) \) at the point \( (1/2, \pi/6) \). Since \( y = \pi/6 \), \( \cos(\pi/6) = \sqrt{3}/2 \). Substitute this into the expression for \( \frac{dy}{dx} \) to find the slope.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Inverse Functions

Inverse functions reverse the effect of the original function. For example, if y = sin(x), then x = sin<sup>-1</sup>(y) is the inverse function. Understanding how to work with inverse functions is crucial for analyzing their properties, such as slopes and behavior at specific points.

Slope of a Curve

The slope of a curve at a given point represents the rate of change of the function at that point. It can be interpreted as the tangent line's steepness at the point of interest. For the curve y = sin<sup>-1</sup>(x), finding the slope at (1/2, π/6) involves understanding the relationship between the function and its inverse.

Trigonometric Identities

Trigonometric identities are equations involving trigonometric functions that hold true for all values of the variables. In this context, knowing the values of sin and cos at specific angles, such as π/6, is essential for determining the slope without directly calculating the derivative. These identities help relate the angles to their sine and cosine values.

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