/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 40 What is the area of an equilater... [FREE SOLUTION] | 91Ó°ÊÓ

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What is the area of an equilateral triangle that has an inscribed circle with an area of \(50 \pi \mathrm{cm}^{2},\) and a circumscribed circle with an area of \(200 \pi \mathrm{cm}^{2} ?\)

Short Answer

Expert verified
The area of the equilateral triangle is \(150\sqrt{3} \ cm^2\).

Step by step solution

01

Understanding the Problem

We need to find the area of an equilateral triangle given that it has an inscribed circle (incircle) with an area of \(50\pi \ cm^2\) and a circumscribed circle (circumcircle) with an area of \(200\pi \ cm^2\).
02

Identify Circumcircle Radius

The area of the circumcircle is given by \(\pi R^2 = 200\pi\). Solving for \(R\), we find \(R^2 = 200\), thus \(R = \sqrt{200} = 10\sqrt{2}\).
03

Identify Incircle Radius

The area of the incircle is given by \(\pi r^2 = 50\pi\). Solving for \(r\), we find \(r^2 = 50\), thus \(r = \sqrt{50} = 5\sqrt{2}\).
04

Establish Relationship in Equilateral Triangle

For an equilateral triangle, there is a relationship between the side length \(a\), the inradius \(r\), and the circumradius \(R\): \(r = \frac{a\sqrt{3}}{6}\) and \(R = \frac{a\sqrt{3}}{3}\).
05

Solve for Side Length \(a\)

From Step 3, substitute the \(r\) value into \(r = \frac{a\sqrt{3}}{6}\): \(5\sqrt{2} = \frac{a\sqrt{3}}{6}\). Solve for \(a\): \(a = 10\sqrt{6}\).
06

Calculate the Area of the Equilateral Triangle

The area \(A\) of an equilateral triangle with side length \(a\) is given by \( A = \frac{\sqrt{3}}{4} a^2 \). Substitute \(a = 10\sqrt{6}\) into this formula: \( A = \frac{\sqrt{3}}{4} (10\sqrt{6})^2 = \frac{\sqrt{3}}{4} \times 600 = 150\sqrt{3} \).
07

Verify Consistency

Verify that the triangle parameters satisfy both radius conditions: Check that \(r = \frac{a\sqrt{3}}{6} = 5\sqrt{2}\) and \(R = \frac{a\sqrt{3}}{3} = 10\sqrt{2}\) hold true for \(a = 10\sqrt{6}\), confirming consistency in our calculations.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Area of Circles
The area of a circle is calculated using the formula \( \pi r^2 \), where \( r \) is the radius of the circle. This means the area depends directly on the radius and grows exponentially as the radius increases. For example, if the radius of a circle doubles, the area quadruples because it's proportional to the square of the radius.
In the provided problem, we have two circles: an incircle and a circumcircle within an equilateral triangle. Knowing the areas of these circles, \( 50\pi \ \text{cm}^2 \) for the incircle and \( 200\pi \ \text{cm}^2 \) for the circumcircle, we can determine their radii. This knowledge allows us to explore further relationships with the triangle to determine its properties.
Geometry
Geometry involves the study of shapes, their properties, and their spatial arrangements. An equilateral triangle has equal sides and angles, each measuring \(60^\circ\). In geometry, specific relationships exist between the elements of an equilateral triangle.
For instance, the triangle's height, area, and the lengths of segments connecting the incenter (for the incircle) or circumcenter (for the circumcircle) to its vertices, all relate through formulas involving trigonometric and geometric principles.
Understanding these relationships makes it easier to solve problems involving equilateral triangles because they provide consistent properties and shortcuts to derive unknown values from known quantities.
Radius Relationship
In geometry, the radius of an incircle and a circumcircle reveals a lot about the triangle itself. The incircle is the largest circle that fits inside the triangle, touching all three sides. Meanwhile, the circumcircle passes through all the triangle’s vertices, encompassing it entirely.
For an equilateral triangle, specific, easily calculable relationships exist between its side length \( a \), its inradius \( r \), and its circumradius \( R \). These relationships are given by:
  • \( r = \frac{a\sqrt{3}}{6} \)
  • \( R = \frac{a\sqrt{3}}{3} \)

These relationships help in finding the side of the triangle when either of the radii is known. They give a consistent method to relate the circle's dimensions back to the equilateral triangle geometrically.
Mathematical Problem Solving
Problem-solving in mathematics often involves breaking down complex problems into smaller, more manageable steps. This method is beneficial in geometry, where relationships between shapes and their properties can simplify solutions.
The original exercise required determining the side length of an equilateral triangle using the areas of its inscribed and circumscribed circles. By first calculating the radii of each circle, and then using known geometric relationships, the problem becomes a sequence of straightforward calculations.
This showcases a common mathematical problem-solving approach: identify known values, use them within established formulas, and verify results for consistency. This strategy ensures accuracy and a deeper understanding of the mathematical principles in play.

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Most popular questions from this chapter

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