How to Find the Area of a Region Inside a Square?

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Discussion Overview

The discussion revolves around finding the area of a shaded region inside a square, specifically the area of points closer to the center of the square than to its edges. The inquiry involves understanding the geometric and mathematical reasoning behind the integration process used to derive the area.

Discussion Character

  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant describes the region as a square with "inflated edges" and mentions that the area calculation involves integration, starting with a symmetry argument and a specific distance calculation.
  • The same participant questions the reasoning behind using the expression x-a/2 to represent the distance from a point to the edge of the square, seeking clarification on its significance.
  • Another participant explains that the distance from a point to a line is determined by the shortest distance, which is found by drawing a perpendicular segment from the point to the line, and prompts the original poster to consider the equations of the square's edges.
  • A later reply expresses gratitude for the clarification provided, indicating that the explanation was helpful in understanding the problem better.

Areas of Agreement / Disagreement

The discussion does not present a consensus, as the original poster is still seeking clarity on the reasoning behind certain mathematical steps, indicating that uncertainty remains regarding the integration process and the distance calculations.

Contextual Notes

The discussion includes assumptions about the geometric properties of the square and the methods of calculating distances, which may not be fully articulated or resolved in the posts.

sciencegem
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Hi,
This question is killing me (please note that it's not homework, this is from self study):
The shaded region inside a square of side "a" consists of all points that are closer to the centre of the square than any of its edges (emphasis on any of its edges--the resulting region is like a square with inflated edges). I know the answer involves integration, in fact I have the entire answer. It begins:
"By symmetry, we consider only the portion of the region between the lines of y=0 and y=x, and then multiply the resulting area by 8. The distance from the origin to point (x, y) on the boundary of the region equals the distance from (x, y) to the line x=a/2, that is, such points satisfy √(x^2 + y^2)=√(x-a/2)^2..." then it solves for x and integrates. The final answer it gives is a^2(4√2 -5)/3 . I'm sorry to be slow, but I'm just not getting it. Why x-a/2? And how is x-a/2 a representative for distance all distances between the centre and the boundary of the region? Any help understanding the intuition behind this answer/a different logical answer would be massively appreciated. Thanks!
 

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The distance between a point and a line is found by finding the shortest distance between the given point and the line. This shortest distance is found by drawing a perpendicular segment from the point to the line. Look at the picture you have. The center of the square is at the origin (0,0).

- What is the equation of the vertical line which forms the right side of the square given that the origin is at the center of the square?
- How far is (x,y) from that line given that you have to draw a perpendicular segment to the line to find the distance?

Junaid Mansuri
 
That was the perfect push in the right direction, thanks so much!
 
You're welcome.
 

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