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 TOPICS This page:   two-dimensional  geometry    Search   Dr. Math See also the Dr. Math FAQ:   geometric formulas and   naming polygons   and polyhedra Internet Library:   Euclidean/plane   geometry ELEMENTARY Arithmetic    addition    subtraction    multiplication    division    fractions/decimals Definitions Geometry    2-dimensional      circles      triangles/polygons    3D and higher      polyhedra Golden Ratio/ Fibonacci Sequence History/Biography Measurement    calendars/      dates/time    temperature    terms/units Number Sense/ About Numbers    infinity    large numbers    place value    prime numbers    square roots Projects Puzzles Word Problems Browse Elementary Two-Dimensional Geometry Stars indicate particularly interesting answers or good places to begin browsing. Selected answers to common questions:     What are length and width? Angles: Acute, Right, Obtuse, Reflex [06/06/2001] How can I remember what the names of angles mean? Area and Perimeter [05/01/2001] I do not understand area and perimeter - can you explain them? Area and Volume [04/10/2002] I cannot figure out how to do volume. Turning a Perimeter into a Scale Factor [02/17/2003] Perimeter and area ratios of similar figures are given. Find each scale factor. Using a Protractor [06/28/1998] How do you construct two parallel lines and intersect them making a 65-degree angle? A 14-Sided Polygon [7/28/1996] What is the proper name for a 14-sided figure? 2 Square Feet vs. 2 Feet Square [11/22/1998] What is the difference between 2 square feet and 2 feet square? 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? Adjacent Angles [09/19/2001] What is the definition of adjacent angles? Area Larger Than Perimeter? [04/15/2002] Can the area of a shape be larger than the perimeter? Area of an L [07/10/2003] How do you find the area of an 'L' shaped object? 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? Circle Area and Circumference [03/16/2002] Are radius and diameter the same as area and circumference? Circumference vs. Perimeter [05/09/2003] Technically speaking, can the term 'perimeter' apply to a circle in a mathematical context? Complementary or Supplementary? [04/02/2001] I keep getting complementary and supplementary mixed up. How can I remember which is which? Coordinates in the Cartesian Plane [01/21/2005] How do I get the coordinates for a point on a graph? Cutting Slits in a Piece of Paper [02/01/2002] How can you cut a hole in a piece of paper so a person can go through it? A Definition of Geometry [2/1/1996] A fifth grader asks Dr. Math to give her a definition of geometry. Deriving the Area Formula for a Circle [03/08/2000] Why is the area of a circle the square of the radius times pi? Dividing Land by Area vs. Perimeter [11/05/1999] What are the advantages of dividing land by area vs. perimeter? Eleven Sections of Fence [05/29/2003] I have a grid containing 16 squares. Each square represents 1 acre. I need to draw 11 sections of fence along the dotted lines of the squares so that 4 fields are formed, each containing 4 acres of land. Equable Shapes [04/26/2001] Is there a rule for how to get equable shapes, that is, shapes with the same area and perimeter? Euler's Formula [11/26/2001] I have to find Euler's formula for two-dimensional figures and explain it at a university level and at an elementary-school level. Figuring Square Footage and Yardage [12/14/2002] What is the exact calculation used in order to determine square footage or yardage of a given room? Flatland, by Edwin Abbott [8/21/1996] I need any info about the book FLATLAND by Edwin Abbott and how it can be used in the classroom. Flips, Reflections, Rotation, and Quadrants [11/10/1998] These terms are being used to describe the movement of shapes. What do they really stand for? Fourth Grade Geometry Questions [4/24/1995] My grade 4 regular education students are wondering if curved lines can be parallel lines. Geometric Objects [4/1/1996] Name objects in the real world that suggest geometric figures, including lines and planes. Intersection of Circles [10/08/1998] I do not understand the term intersection in geometry. Learning Proofs [12/19/1995] I'm a fourth grader interested in learning how to do proofs. Can you recommend some good books on the different techniques used and how they are applied? Left Angles [06/01/1999] What is a left angle? Line Segments and the Origins of Geometry [6/7/1995] How can segments be lines? Why is geometry called geometry? Mobius Strips, Spheres, and Dimensionality [05/28/2003] Is a Mobius Strip 2-D or 3-D? Or is it 1-D? What about a sphere? Obtuse angles [11/10/1994] What is an obtuse angle? One Dimension [05/13/2003] Is there such a thing as 1D? Planting Trees [08/13/2002] I have to plant 10 trees in 5 rows with 4 trees in each row. Polyominos [08/11/1999] What is the definition of a polyomino? Rays and Angles [11/24/1997] Do rays have an arrow on both ends, or is that an angle? Page:  1  2 [next>]

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