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## Solve contextual problems involving similar triangles. SPI 0706.4.1

1. A Mathematical Droodle - Two Triples of Similar Triangles or 2. Compass and Straightedge Construction of Similar Triangles - lesson plan from PlanetMath 3. Connecting Geometry: Similar Triangles - Similar triangles can be very useful for measuring inaccessible objects. One method of doing this is called "shadow reckoning," which this page describes
4. Indirect Measurement with Similar Triangles - this five page lesson plan describes how to use a mirror in making indirect measurements. [This expired link is available through the Wayback Machine Internet Archive. If the page doesn't load quickly click on Impatient? at the bottom right of the page.]  5. Math Open Reference: Similar Triangles - interactive triangle lesson or 6. Measuring Angles - use a virtual protractor or 7. Proof Using Similar Triangles - four examples to print and use in your classroom  8. Proportionality in Similar Triangles: A Cross-Cultural Comparison - a lesson plan from Convergence: a magazine of the Mathematical Association of America [This expired link is available through the Wayback Machine Internet Archive. If the page doesn't load quickly click on Impatient? at the bottom right of the page.] 9. Protractor - learn how to position and read a protractor in order to measure an angle, and how to use either scale on the protractor or 10. Similar Triangles - a 23 slide PowerPoint show which includes scaling factors
11. Similar Triangles II - a 14 slide PowerPoint show
12. Similar Triangles - explanation of the concept
13. Similar Triangles - includes the AA rule and the RAR rule plus two videos 14. Similar Triangles and Indirect Measurement - this worksheet gives a short review, an example and five practice problems  15. Similar Triangles and the Pythagorean theorem - from Dave's Short Trig Course
16. Strategies for Dealing with Similar Triangles - from Oswego City School District Regents Exam Prep Center
17. Sum of Angles in a Triangle - students can explore this concept by moving the vertices of the triangle with pressed mouse button or 18. Three Similar Triangles - a math droodle or 19. Triangle Calculator - Enter values three of the six sides and angles of the triangle and the other three values will be computed. The number of significant values entered will determine the number of significant figures in the results.
20. Understanding Scale Factors - Similar Triangles: Perimeters and Areas - When two triangles are similar, the reduced ratio of any two corresponding sides is called the scale factor of the similar triangles
21. Using Similar Triangles and Rectangles - in this investigation, you can use similar triangles to estimate heights and distances that are difficult to measure directly 22. Virtual Manipulative - Similar Triangles or  Internet4classrooms is a collaborative effort by Susan Brooks and Bill Byles. 