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Ch. 4 - Applications of Derivatives
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
Chapter 4, Problem 4.7.77

Initial Value Problems


Solve the initial value problems in Exercises 71–90.


ds/dt = 1 + cos t, s(0) = 4

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1
Identify the given differential equation and initial condition: \( \frac{ds}{dt} = 1 + \cos t \) with \( s(0) = 4 \).
Recognize that this is a first-order ordinary differential equation where \( s(t) \) is the unknown function and \( t \) is the independent variable.
Integrate both sides of the equation with respect to \( t \) to find \( s(t) \): \[ s(t) = \int (1 + \cos t) \, dt + C \]
Compute the integral on the right-hand side by integrating each term separately: \[ \int 1 \, dt = t \] and \[ \int \cos t \, dt = \sin t \]
Use the initial condition \( s(0) = 4 \) to solve for the constant of integration \( C \) by substituting \( t = 0 \) into the expression for \( s(t) \) and setting it equal to 4.

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Key Concepts

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

Differential Equations

A differential equation relates a function with its derivatives. Solving it means finding the original function that satisfies the given relationship between the function and its rate of change.
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Initial Value Problem (IVP)

An IVP specifies a differential equation along with a condition that the solution must satisfy at a particular point, such as s(0) = 4. This condition helps determine the unique solution to the differential equation.
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Integration of Trigonometric Functions

Solving ds/dt = 1 + cos t requires integrating the right-hand side with respect to t. Knowing how to integrate basic trigonometric functions like cosine is essential to find the general solution.
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Introduction to Trigonometric Functions