Chapter 10: Problem 37
The radius of circle \(B\) is 2.5 times the radius of circle \(A .\) If the area of circle \(A\) is 8 square yards, what is the area of circle \(B ?\) (CIRCLE CANNOT COPY)
Short Answer
Expert verified
The area of circle B is 50 square yards.
Step by step solution
01
Understanding the Relationship
First, we identify that the radius of circle B is 2.5 times that of circle A. Thus, if the radius of circle A is denoted as \( r_A \), then the radius of circle B, \( r_B \), can be written as \( r_B = 2.5 \times r_A \).
02
Finding the Radius of Circle A
We know the area of circle A is given by \[\text{Area of circle A} = \pi \times (r_A)^2 = 8\]Solving for \( r_A \), we have:\[(r_A)^2 = \frac{8}{\pi}\]Thus, the radius of circle A is \[ r_A = \sqrt{\frac{8}{\pi}} \].
03
Calculating the Radius of Circle B
Substituting the expression for \( r_A \) into the relationship for \( r_B \), we find:\[ r_B = 2.5 \times \sqrt{\frac{8}{\pi}}\]
04
Finding the Area of Circle B
The area of circle B is given by the formula\[\text{Area of circle B} = \pi \times (r_B)^2\]Substituting the value of \( r_B \) we found:\[\text{Area of circle B} = \pi \times \left(2.5 \times \sqrt{\frac{8}{\pi}}\right)^2\]Simplifying further, we have:\[\text{Area of circle B} = \pi \times \left(6.25 \times \frac{8}{\pi}\right) = 6.25 \times 8 = 50\]Therefore, the area of circle B is 50 square yards.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Radius Calculation
The radius of a circle is a crucial dimension that can unlock other geometric properties of the circle, such as its area and circumference. In our problem, we deal with two circles, A and B. To calculate the radius of each circle, we started with circle A. For any circle, the area can be given by the formula:
- Area = \(\pi \times r^2\)
- \(\pi \times (r_A)^2 = 8\)
- \((r_A)^2 = \frac{8}{\pi}\)
- \(r_A = \sqrt{\frac{8}{\pi}}\)
Circle Geometry
Circle geometry is the study of properties and measures of a circle, focusing primarily on parameters such as radius, diameter, circumference, and area. One of the foundational aspects of geometry is understanding how these elements are related. Let’s break these down:
- Radius (r): The distance from the center of the circle to any point on its circumference.
- Diameter (d): Twice the radius, or the longest distance across the circle, passing through the center.
- Area (A): Calculated as \( \pi r^2 \), which measures the space contained within the circle.
- Circumference (C): The total distance around the circle, calculated as \( 2\pi r \).
Problem-Solving Steps
Solving problems in mathematics often involves a systematic approach to bridge known concepts to the unknown quantities you wish to determine. In this area calculation problem, we followed specific steps:
- Step 1: Understanding the Relationship: Recognize the relation between the radius of circle B and circle A. This fundamental observation laid the groundwork for further calculations.
- Step 2: Calculating Radius of Circle A: Use the circle area formula and given area to derive the radius of circle A.
- Step 3: Calculating the Radius of Circle B: Utilize the relationship that \( r_B = 2.5 \times r_A \) to find circle B's radius.
- Step 4: Calculating the Area of Circle B: Substitute the expression for \( r_B \) back into the area formula to find circle B's area.