2. Properties of Rectangles
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l • Quadrilateral with 2
2
Parallel Sides
w • Length
1
4
• Width
• All 4 angles are 90°
3. Geometry of a Rectangle
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l • Area = l x w
1
2
w • Perimeter = (2 x l) + (2 x w)
4
4. Application
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1
2
4
• You would like to put a new stone border around your
yard. Before your tape measure broke, you determined the
width of the yard to be 7 feet. You also know (from when
you bought the home) that the yard is 105 square feet.
How much stone is needed to build the border?
5. Solution/Conclusion
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• We need to find Perimeter but we don’t know the
2
length of the yard.
1
• Since A = l x w
4
– l = A / w = 105 square feet / 7 feet
– l = 15 feet
• Perimeter = (2 x l) + (2 x w)
– P = (2 x 15 feet) + (2 x 7 feet)
• Perimeter = 44 feet
Editor's Notes
After normal class introduction routine, begin to ask the class about examples of rectangular shaped objects. Transition to showing and discussing some of the examples of the slide. The motivation for this lesson is the real world application for what they learn about rectangles. Images retrieved from http://exploringsciencewiki.wikidot.com/artificial-vs-natural-patterns and http://www.archsociety.com/comment.php?comment.news.100 on October 5, 2012
Describe that the main properties of the rectangle, I will begin by reviewing/questioning the class on quadrilaterals and parallel topics, and point out the 2 parallel sides of the rectangle. Discuss that rectangles have a length and width and point out that rectangles that have equal lengths and widths are squares. Lastly, describe that all 4 of a rectangles equal 90 degrees.
Introduce the geometric equations of the rectangle. Call attention to the fact that both the area and perimeter equations rely on the length and the width.
Introduce a problem that ties in the learning and presents a potential real world application to what they learned. At this point, depending on the class, either work through the problem (next slide) or give the class time to work on the problem by themselves or in small groups. Image retrieved from http://www.distroarchitecture.com/welcoming-and-pleasing-nice-smal-garden-concept-with-wooden-deck on October 5, 2012.
At this point the class will work through the problem solution. Consider having a student or students step through the solution at front of class, only reveal the steps to the solution as the class works through it. Conclude the lesson by reiterating why rectangle geometry is important and relevant. Also restate the important rectangle properties and equations.
