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### Area of a Rectangle Outside a Rectangle

```
Date: 6/11/96 at 2:20:13
From: Anonymous
Subject: Area of a rectangle not in another rectangle

A rectangular swimming pool 50 m by 32 m has a concrete border
all around it.  Find the area of the concrete border if it is
2.4 m wide at the sides and 4.8 m wide at the ends.  The concrete path
is to be tiled with square tiles of side 20 cm each.  How many tiles
will be needed?

A big group of Singaporean friends and I have been stumped over this
question. We sincerely hope that you can help us. There seem to
be many different ways to do this question and the answers range
widely.

Yours sincerely,
Jeannette signin' off from Sunny Singapore
```

```
Date: 6/12/96 at 13:46:52
From: Doctor Darren
Subject: Re: Area of a rectangle not in another rectangle

I would approach this problem by finding the area of the rectangle
you want _including_ the path and the pool (which has length
50+2*4.8 = 59.6 m, and width 32+2*2.4 = 36.8 m) so the area is
2193.28 m^2.  We then subtract the area of the pool, which is
1600 m^2, and the area of the concrete border is 593.28 m^2.

-Doctor Darren,  The Math Forum
Check out our web site!  http://mathforum.org/dr.math/
```
Associated Topics:
High School Euclidean/Plane Geometry
High School Geometry
High School Triangles and Other Polygons
Middle School Geometry
Middle School Triangles and Other Polygons
Middle School Two-Dimensional Geometry

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