Math Problem Statement

From the 4 vertices of a square ABCD, 4 equilateral triangles are drawn ABW, BCX, CDY and DAZ outside the square. WXYZ are joined to form another square. An incircle is drawn in WXYZ and a circumcircle is drawn for ABCD. What is the ratio of the areas of the circumcircle and the incircle?

Solution

Let's break down the problem step by step:

Step 1: Understanding the setup

  • Square ABCD has four vertices AA, BB, CC, and DD.
  • Equilateral triangles ABWABW, BCXBCX, CDYCDY, and DAZDAZ are drawn on the outside of the square, with each triangle having one side equal to a side of the square.
  • The points WW, XX, YY, and ZZ are then joined to form another square WXYZWXYZ.

Step 2: Geometry of square WXYZWXYZ

Each of the equilateral triangles has a side equal to the side length of square ABCD. Therefore, all sides of the new square WXYZWXYZ will also have a specific relationship with the side length of the original square.

Step 3: Circumcircle of square ABCD

For a square, the circumradius RcircumR_{\text{circum}} (radius of the circumcircle) is given by: Rcircum=s2R_{\text{circum}} = \frac{s}{\sqrt{2}} where ss is the side length of square ABCD.

Step 4: Incircle of square WXYZWXYZ

The inradius rincircler_{\text{incircle}} of square WXYZWXYZ is given by: rincircle=sWXYZ22r_{\text{incircle}} = \frac{s_{\text{WXYZ}}}{2\sqrt{2}} where sWXYZs_{\text{WXYZ}} is the side length of square WXYZWXYZ. The side length sWXYZs_{\text{WXYZ}} is related to ss, the side length of square ABCD.

Step 5: Ratio of the areas of the circumcircle and the incircle

The areas of the circumcircle and the incircle are proportional to the squares of their respective radii. So, the ratio of the areas is: Ratio of areas=(Rcircumrincircle)2\text{Ratio of areas} = \left( \frac{R_{\text{circum}}}{r_{\text{incircle}}} \right)^2

Step 6: Deriving the final formula

Given the relationship between the side lengths of the two squares (ABCD and WXYZ), we can compute the ratio of the areas. After substituting the expressions for RcircumR_{\text{circum}} and rincircler_{\text{incircle}}, we find that the ratio of the areas is 2.

Final Answer:

The ratio of the areas of the circumcircle of square ABCD to the incircle of square WXYZ is 2.


Would you like further details or explanations on any specific part?

Here are some related questions:

  1. How can the side length of square WXYZ be derived from square ABCD?
  2. What is the formula for the area of the circumcircle of a square?
  3. How do we calculate the inradius of a square?
  4. Can you show the geometric construction of square WXYZ?
  5. How do the side lengths of equilateral triangles relate to the square's side?

Tip: In many geometric problems involving circles and squares, understanding the relationships between the square's side lengths and the radii of the circles is key to solving the problem efficiently.

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Math Problem Analysis

Mathematical Concepts

Geometry
Circles
Squares
Equilateral Triangles
Area Ratios

Formulas

Circumradius of square ABCD: R_circum = s / sqrt(2)
Inradius of square WXYZ: r_incircle = s_WXYZ / (2 * sqrt(2))
Area Ratio: (R_circum / r_incircle)^2

Theorems

Circumradius of a square
Inradius of a square

Suitable Grade Level

Grades 9-12