The bottom of a large theater screen is 3 ft above your eye level and the top of the screen is 10 ft above your eye level. Assume you walk away from the screen (perpendicular to the screen) at a rate of 3 ft/s while looking at the screen. What is the rate of change of the viewing angle θ when you are 30 ft from the wall on which the screen hangs, assuming the floor is horizontal (see figure)? <IMAGE>
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- 0. Functions7h 52m
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4. Applications of Derivatives
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Problem 3.6.29a
Textbook Question
Consider the following cost functions.
a. Find the average cost and marginal cost functions.
C(x) = 1000+0.1x, 0≤x≤5000, a=2000

1
To find the average cost function, divide the total cost function C(x) by the number of units x. The average cost function A(x) is given by A(x) = C(x) / x.
Substitute the given cost function C(x) = 1000 + 0.1x into the average cost formula: A(x) = (1000 + 0.1x) / x.
Simplify the expression for A(x) to get A(x) = 1000/x + 0.1.
To find the marginal cost function, take the derivative of the total cost function C(x) with respect to x. The marginal cost function MC(x) is given by MC(x) = dC(x)/dx.
Differentiate C(x) = 1000 + 0.1x with respect to x. Since the derivative of a constant is 0 and the derivative of 0.1x is 0.1, the marginal cost function MC(x) = 0.1.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Average Cost Function
The average cost function, denoted as AC(x), represents the total cost C(x) divided by the quantity produced x. It provides insight into the cost per unit of production, helping businesses determine pricing strategies. For the given cost function C(x) = 1000 + 0.1x, the average cost can be calculated as AC(x) = C(x)/x, which simplifies to (1000/x) + 0.1.
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Marginal Cost Function
The marginal cost function, denoted as MC(x), measures the additional cost incurred by producing one more unit of output. It is derived from the derivative of the total cost function C(x) with respect to x. For the cost function C(x) = 1000 + 0.1x, the marginal cost is found by calculating MC(x) = dC/dx, which results in a constant value of 0.1, indicating that each additional unit costs 0.1.
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Properties of Functions
Cost Function
A cost function describes the relationship between the quantity of output produced and the total cost incurred in production. It typically includes fixed costs, which do not change with output, and variable costs, which do. In the provided function C(x) = 1000 + 0.1x, the fixed cost is 1000, while the variable cost is represented by the term 0.1x, indicating that costs increase linearly with production.
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Properties of Functions
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