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Ch. 1 - Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 1, Problema 1

Functions and Graphs


Express the area and circumference of a circle as functions of the circle’s radius. Then express the area as a function of the circumference.

Guida verificata passo dopo passo
1
Start by recalling the formulas for the area and circumference of a circle. The area \( A \) of a circle is given by \( A = \pi r^2 \), where \( r \) is the radius. The circumference \( C \) is given by \( C = 2\pi r \).
Express the area \( A \) as a function of the radius \( r \). This is already given by the formula \( A(r) = \pi r^2 \).
Express the circumference \( C \) as a function of the radius \( r \). This is given by the formula \( C(r) = 2\pi r \).
To express the area as a function of the circumference, first solve the circumference formula for \( r \). From \( C = 2\pi r \), we get \( r = \frac{C}{2\pi} \).
Substitute \( r = \frac{C}{2\pi} \) into the area formula \( A = \pi r^2 \) to express the area as a function of the circumference: \( A(C) = \pi \left(\frac{C}{2\pi}\right)^2 \). Simplify this expression to complete the function.

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Area of a Circle

The area of a circle is calculated using the formula A = πr², where A represents the area and r is the radius. This formula shows that the area is directly proportional to the square of the radius, meaning that as the radius increases, the area increases quadratically.
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Estimating the Area Under a Curve with Right Endpoints & Midpoint

Circumference of a Circle

The circumference of a circle is given by the formula C = 2πr, where C is the circumference and r is the radius. This formula indicates that the circumference is directly proportional to the radius, meaning that if the radius doubles, the circumference also doubles.
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Evaluate Composite Functions - Values on Unit Circle

Function Relationships

In this context, expressing the area as a function of the circumference involves manipulating the formulas for area and circumference. By substituting the expression for radius from the circumference formula into the area formula, we can derive a new function A(C) that relates area directly to circumference.
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Graphs of Secant and Cosecant Functions