Chapter 11: Problem 10
Find the area of each circle described to the nearest hundredth. \(r=6.7 \mathrm{~cm}\)
Short Answer
Expert verified
The area of the circle is approximately 141.37 cm².
Step by step solution
01
Identify the Formula
The area of a circle is calculated using the formula: \[ A = \pi r^2 \] where \( A \) is the area and \( r \) is the radius of the circle. In this problem, the radius \( r \) is given as \( 6.7 \) cm.
02
Plug in the Radius
Substitute \( r = 6.7 \) cm into the formula: \[ A = \pi (6.7)^2 \]
03
Calculate the Square of the Radius
First, calculate \( (6.7)^2 \): \[ (6.7)^2 = 44.89 \]
04
Calculate the Area
Now, substitute the squared radius into the formula and multiply by \( \pi \): \[ A = \pi \times 44.89 \approx 141.37 \text{ cm}^2 \] Here, \( \pi \approx 3.14159 \) is used.
05
Round the Result
Finally, round the calculated area to the nearest hundredth: \[ A \approx 141.37 \text{ cm}^2 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Radius
The radius of a circle is the distance from the center of the circle to any point on its edge. It's a crucial component when calculating the area of a circle, as it directly influences the size of the circle.
- The radius is always half of the diameter, which is the distance across the circle passing through the center.
- In the given problem, the radius is 6.7 cm. This specific length determines how broad the circle will be and subsequently affects the calculation of the area.
Pi
Pi (Ï€) is a mathematical constant that represents the ratio of the circumference of any circle to its diameter. It is a significant and interesting number in mathematics.
- Pi is approximately 3.14159 and is indicated by the Greek letter 'Ï€'.
- It is an irrational number, meaning it cannot be exactly written as a simple fraction, and its exact value goes on infinitely without repeating.
Circle Area Formula
The circle area formula is a mathematical equation used to determine the amount of space inside a circle. The formula is beautifully simple: \[ A = \pi r^2 \]Here, \( A \) represents the area, \( \pi \) is pi (about 3.14159), and \( r \) is the radius of the circle. This relationship shows how both pi and the radius are essential for calculating the area.
- The square of the radius, \( r^2 \), helps transition our radius measurement into squared units which represent area, rather than just length.
- Multiplying by pi scales the squared radius into a circle's actual area, due to the constant nature of pi found in circular calculations.