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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 MIDDLE SCHOOL About Math Algebra    equations    factoring expressions    graphing equations Arithmetic    division    exponents    factorials    factoring numbers    fractions/percents    logarithms Definitions Geometry    2-dimensional      conic sections/        circles      triangles/polygons    3D and higher      polyhedra History/Biography Logic Measurement    calendars/      dates/time    temperature    terms/units Number Sense    factoring numbers    negative numbers    pi    prime numbers    square roots Probability Puzzles Ratio/Proportion Statistics Word Problems Browse Middle School Two-Dimensional Geometry Stars indicate particularly interesting answers or good places to begin browsing. Selected answers to common questions:     Classifying quadrilaterals.     Pythagorean theorem proofs. Transversal - Meaning and Examples [11/14/1994] I have a 7th grade student who would like to know the meaning and examples of "transversal". A Triangle with Three Right Angles [12/01/1999] How can you make a triangle with three right angles? Trisecting a Line [11/03/1997] How would you trisect a line using a compass and a straight edge? Trisecting a Line [01/30/1998] How do I trisect a line using only a straightedge and compass? Trisecting a Line Segment [08/13/1999] How can I measure one-third of a line of an unknown length using a compass and a straightedge? Trisecting an Angle [4/16/1996] I can bisect an angle easily but I can't trisect it perfectly. Would you please send me instructions? Trisecting Angles [5/30/1995] Can an angle be trisected? Trisecting a Right Angle [12/16/1996] An explanation of how to trisect a 90 degree angle, plus some constructions. Two Column Proof of a Theorem [08/12/1998] Write a two-column proof and give numbered statements with reasons.... The Unknown Angle that Didn't Matter [10/01/2014] A geometry word problem leads to the confounding result 120° equals 0. Doctor Ian takes a closer look at how to interpret this puzzle's statement — and empty solution sets generally. Using a Protractor [8/15/1996] How do I measure angles using a protractor? Vertical Angle [11/15/2001] What are vertical angles? Are they equal? Vertical Angles [10/27/1996] What are vertical angles? What Are Proofs? [08/12/1997] I am homeschooling and do not understand proofs. Can you help me out? What is a Jordan Curve? [06/07/2006] What is a simple definition of a Jordan curve I can give my 5th graders? What is a point? [8/26/1996] Define a point, please. What Is a Theorem and Why Are They Important? [08/15/1997] I don't understand how theorems help us learn. What is a Vertex? [12/06/2001] And what does vertices mean? What is Dimensional Analysis? [11/26/2001] What is dimensional analysis and how does it work? What is Geometry For? [03/01/2002] What is geometry really for? When Does 2D Become 3D? [01/20/2003] Is a piece of paper a 3D object when held up in space? Or is it a 2D object in 3D space? When is the expression Q.E.D. used? [02/15/1999] More on Q.E.D. Why Cubed? [11/27/2001] Why do we use "cubed" for the volume of a figure? Why is K Used as an Abbreviation for Area? [11/29/2004] Many textbooks use the letter K to represent area in formulas, instead of A. Do you know why that is? Why Proofs? Definitions and Axioms [09/16/2001] Why are proofs important in the development of a mathematical system like geometry? Why Study Tangrams? [10/27/1999] How can a person use tangrams in the real world? World War II Window Blackout [10/21/2001] Mr. Brown had a square window 120cm x 120cm, but the only material he could find was a sheet of plywood 160cm x 90cm; same area, different shape. He drew some lines and cut out just two congruent shapes, which he joined to make a square of the correct size. How did he do it? Zero Degree and 360 Degree Angles [10/22/2003] I am curious if there is such a thing as a zero degree angle, and if so, what does it look like? I am also wondering if a zero degree angle equals a 360 degree angle? I understand that a 360 degree angle is essentially a circle, or the amount of 'turn' that equals a circle. I am pondering how you would draw a 360 degree angle? Page: [

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