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Ch. 3 - Derivatives
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
All textbooksBriggs 3rd EditionCh. 3 - DerivativesProblem 3.8.19b
Chapter 3, Problem 3.8.19b

13-26 Implicit differentiation Carry out the following steps.
b. Find the slope of the curve at the given point.
cos y = x; (0, π/2)

Verified step by step guidance
1
Start by differentiating both sides of the equation with respect to x. For the left side, differentiate cos(y) using the chain rule: the derivative of cos(y) is -sin(y) times the derivative of y with respect to x, which is dy/dx. For the right side, the derivative of x is 1.
Write the differentiated equation: -sin(y) * (dy/dx) = 1.
Solve for dy/dx by isolating it on one side of the equation. This involves dividing both sides by -sin(y), giving dy/dx = -1/sin(y).
Substitute the given point (0, π/2) into the equation to find the slope at that point. Since y = π/2, substitute π/2 for y in the expression for dy/dx.
Evaluate sin(π/2) to find the slope. Since sin(π/2) = 1, substitute this value into the expression for dy/dx to find the slope at the point (0, π/2).

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Key Concepts

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

Implicit Differentiation

Implicit differentiation is a technique used to differentiate equations where the dependent and independent variables are not explicitly separated. Instead of solving for one variable in terms of the other, we differentiate both sides of the equation with respect to the independent variable, applying the chain rule as necessary. This method is particularly useful for curves defined by equations that cannot be easily rearranged.
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Finding The Implicit Derivative

Slope of a Curve

The slope of a curve at a given point represents the rate of change of the dependent variable with respect to the independent variable at that specific point. Mathematically, it is found by evaluating the derivative of the function at that point. In the context of implicit differentiation, the slope can be expressed as dy/dx, which indicates how y changes with respect to x.
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Summary of Curve Sketching

Evaluating Derivatives at a Point

To find the slope of a curve at a specific point, we first compute the derivative of the function and then substitute the coordinates of the point into this derivative. This process allows us to determine the instantaneous rate of change at that point. For the given problem, substituting the point (0, π/2) into the derived expression for dy/dx will yield the slope of the curve at that location.
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Related Practice
Textbook Question

An object oscillates along a vertical line, and its position in centimeters is given by y(t) = 30(sint - 1), where t ≥ 0 is measured in seconds and y is positive in the upward direction.

Find the velocity of the oscillator, v(t) =y′(t).

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Textbook Question

The Chain Rule for second derivatives

b. Use the formula in part (a) to calculate d2dx2(sin(3x4+5x2+2))\(\frac{d^2}{dx^2}\[\left\)(\(\sin\]\left\)(3x^4+5x^2+2\(\right\))\(\right\)).

408
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Textbook Question

For what values of x does g(x) = x−sin x have a slope of 1?

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Textbook Question

{Use of Tech} Power and energy The total energy in megawatt-hr (MWh) used by a town is given by E(t) = 400t+2400/π sin πt/12, where t≥0 is measured in hours, with t=0 corresponding to noon.

b. At what time of day is the rate of energy consumption a maximum? What is the power at that time of day?

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Textbook Question

109-112 {Use of Tech} Calculating limits The following limits are the derivatives of a composite function g at a point a.

b. Use the Chain Rule to find each limit. Verify your answer by using a calculator.

limx→04+sin(x)−2x{\(\displaystyle\]\lim\)_{x\(\to\)0}}\(\frac{\sqrt{4+\sin\left(x\right)}\)-2}{x}

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Textbook Question

13-26 Implicit differentiation Carry out the following steps.

b. Find the slope of the curve at the given point.

sin y = 5x⁴−5; (1, π)

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