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Elementary Archive

Browse Elementary Triangles and Other Polygons

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A 14-Sided Polygon [7/28/1996]

What is the proper name for a 14-sided figure?

7-, 9-Sided Polygons [9/13/1996]

What is the name of a 7-sided figure? a 9-sided figure? Is one of these ever called a septagon? If "septi" means seven, why is September the 9th month of the year?

Area and Perimeter [05/01/2001]

I do not understand area and perimeter - can you explain them?

Area of a Parallelogram [01/07/1999]

How can the area of a parallelogram be the same as the area of a rectangle?

Areas of Figures Broken into Rectangles [10/17/2001]

Calculate the area of each figure. First divide the figure into rectangles and squares...

Area: Triangle vs. Rectangle [4/30/1996]

Why do you have to use a different formula to get the area of a triangle than a rectangle or square?

Area vs. Perimeter of Rectangles [03/19/2000]

Can you explain how two rectangles with exactly the same perimeter can enclose different areas?

Are Squares Rectangles? Are Rectangles Squares? [03/29/2004]

Can a rectangle be a square? I just was wondering because I know a square can be a rectangle.

Axes of Symmetry [2/3/1996]

Can you help a year 5 student understand axes of symmetry of a triangle?

Concave and Convex Polygons [08/13/2001]

What's the difference between a convex and a concave polygon?

Decagons [05/04/1997]

What does a decagon look like?

Defining the Term Oblong [05/15/2000]

Can you give a definition of the term "oblong"?

Describing a Rhombus [01/17/1997]

What is a rhombus?

A Diamond Is Forever Unclear, as A Term -- and How to Teach from That [12/17/2010]

A teacher wonders what the term "diamond" might mean mathematically. Emphasizing that orientation does not enter into polygon classification, Doctors Ian and Rick each suggest ways to take colloquial meaning, and ambiguity, as springboards to motivate fertile discussion, noticing, and wondering.

Distance Between Opposite Corners of a Box [05/09/2002]

A moth is sitting in the lower left front corner of a storage shed. What is the length of the shortest path that the moth can fly to the upper right back corner of the shed?

Equable Shapes [04/26/2001]

Is there a rule for how to get equable shapes, that is, shapes with the same area and perimeter?

Equilateral, Isosceles, Scalene - Word Origins [12/09/2001]

I need to find out about the origins of the scalene, isoceles, and equilateral triangles. How they were named?

Etymology of the Word Rectangle [02/07/2003]

Where does the word 'rectangle' come from?

Etymology of the Word Rhombus [01/30/2003]

Where does the word rhombus come from?

Finding the Perimeter and Area [12/01/1998]

I don't understand how to do perimeter and area in shapes such as a parallelogram and trapezoid.

Finding Total Area of Several Rectangles [07/08/2005]

I need to find the total square footage of a lot of rectangular lawns. Do I have to find the area of each lawn and add up all the areas, or can I just add all the lengths and all the widths and make one area calculation based on those two totals?

How Many Border Stamps? [04/17/2001]

How many stamps are on the border of a 10x10 sheet of 100 stamps?

How to Make a Square with Three Lines [06/19/2001]

My teacher says it is possible to make a square with three lines, but I don't know how to do it. Can you help me?

How Wide is the Garden? [01/06/1998]

A rectangular garden has a 136-ft. fence around it. The garden is 40 feet long. How wide is it?

Is a Square a Rectangle? [06/04/1997]

Are squares rectangles? What is a pentagon?

Is a Square a Rhombus? [8/30/1996]

I've come across different definitions of a "rhombus" that make it unclear whether a square is a rhombus.

Is Kite the True Name? [03/29/2002]

Is kite the true math name for this shape, or is there another?

Kites And Triangles [11/02/1998]

What are kites, and how are they related to triangles?

Leg of a Triangle [04/02/2002]

I need to know where the name "leg" of a triangle comes from, or what its origin is.

Letter Names for Triangles [05/16/2000]

When a triangle is named by the letters of its vertices, why are the letters in the order they are? Could they be in any order?

Logo Area [03/26/2003]

How do we find the area in square units following a Logo command?

Making a Parallelogram [06/19/2001]

Make five shapes - a parallelogram, a square, and three triangles - into one parallelogram.

Name That Polygon [12/03/1999]

Can you help me figure out what kind of polygons are being described based on these clues?

Nonagon or Enneagon? [02/06/2003]

Is 'enneagon' really the correct name for a 9-sided polygon?

Pentagram [12/08/2001]

Is a five-pointed star on a flag a decagon? Or just five triangles?

Picture of Icosahedron [7/31/1996]

Do you have a picture of an icosahedron?

Polygon Diagrams [05/11/2003]

I would like to see pictures of polygons with 11, 12, 13, 14, and 15 sides.

Polygon Names [09/18/2001]

Why is a 3-sided polygon called a triangle instead of a tri-gon? Why is a 4-sided polygon called a quadrilateral instead of a tetragon, when all the others are ___-gons? Why is there not a single consistent term?

Pythagorean Theorem [5/14/1996]

What is the Pythagorean theorem?

Quadrilateral Classification: Definition of a Trapezoid [01/15/1997]

What is the correct definition of a trapezoid, and why?

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