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daily12000-01-01T12:00+00:00Geometry Module 2: Similarity, Proof, and Trigonometry
https://www.oercommons.org/courses/geometry-module-2-similarity-proof-and-trigonometry
Just as rigid motions are used to define congruence in Module 1, so dilations are added to define similarity in Module 2. To be able to discuss similarity, students must first have a clear understanding of how dilations behave. This is done in two parts, by studying how dilations yield scale drawings and reasoning why the properties of dilations must be true. Once dilations are clearly established, similarity transformations are defined and length and angle relationships are examined, yielding triangle similarity criteria. An in-depth look at similarity within right triangles follows, and finally the module ends with a study of right triangle trigonometry.Geometry2016-05-26T16:49:01.063327Course Related MaterialsGeometry Deductive Proof Relay
https://www.oercommons.org/authoring/12083-geometry-deductive-proof-relay
Students engage in a competitive group relay to construct formal proofs involving triangles.
New proofs can always be written to fit different curriculum and pacing. Chariya FisherMathematics2016-02-12T12:52:53.049663Open Author MaterialsBuilding with Triangles
https://www.oercommons.org/courses/building-with-triangles-2
This 3 lesson instructional unit helps students investigate many different aspects of triangles including basic properties of triangles, building other shapes from triangles, the dependence of the third side length on the other two (Triangle Inequality Theorem), and the Sierpinski Triangle fractal. The lesson includes student activity sheets and links to interactive applets.Marea W. ChannelEducationMathematicsGeometry2016-02-07T21:36:24.258733Course Related MaterialsTriangles calculator - TrianCal
https://www.oercommons.org/courses/triangles-calculator-triancal
http://TrianCal.esy.es - Open in Google Chrome. (Triangles online calculator developed by Jesus S.)
YouTube: https://youtu.be/V2IV7lY52mA
I propose this free online calculator triangles without advertising to help students with geometry, does not perform the duties, because their calculations formulas are not displayed. It is designed in a didactic way to check and view the realized duties.
TrianCal is online calculator triangles that works with any combination of values including sides, heights, angles, the area or perimeter of any triangle, calculating it with the minimum possible value (typically three).
Other functions:
- Draw the triangle (s) with GeoGebra.
- Set the range of values in each element.
- The type of angle.
- The type of triangle by its angles and sides.
- Selection of language (English or Spanish).
- Select the angle type [degrees (°), radians, degrees, minutes and seconds (° ' ") or degrees and minutes (° ')].
- Number of decimal places shown in the results (0-15).
- You can use the arrow keys and the Tab key to navigate through the settings.
- Drop-down menu to select the values comfortably.
- Create a link (URL) to the current triangle.
- An icon mail to communicate with the author.
NOTE: You must use the Google Chrome browser to display correctly TrianCal.
Examples of possible combinations:
- The area, perimeter and other data (side, height or angle), if the outside equilateral triangle would not need the third data.
- 2 angles and other data (if the value of the other data is not put aside the value of "a" at the time of drawing the triangle is 10).
- One side, one high and one angle.
- 3 heights.
- 3 sides.
- 2 heights and perimeter.
- Any other combination of values.
MathematicsGeometry2015-12-28T10:48:13.790336Course Related MaterialsMirror, Mirror
https://www.oercommons.org/courses/mirror-mirror-4
In this math lesson, learners use hinged mirrors to discover that regular polygons are composed of triangles tessellating around a center point. Learners then sketch these triangles on paper models of regular polygons with 3 to 10 sides and compute the measure of the center angles formed by these triangles in each of the different polygons. Next, learners explore geometric concepts as they use mirrors and paper polygons to determine which regular polygons tessellate. Learners are challenged to give reasons why some polygons tessellate and others do not.PBSUS Department of EducationEducationMathematicsGeometry2015-12-28T02:08:29.022584Course Related Materials