Ratios and Proportions
Designed for use by Teacher Credential Candidates and undergraduates at UC Irvine.
Table of Contents
- Investigating Similar Figures
- Similar Triangles with Scale Factor Slider
- Create Similar Triangles
- Investigating similar triangles
- The meaning of similar figures
- Proportional Reasoning
- Properties of Similar Figures
- ACCESS - Triangle Proportionality
- Angle Bisectors and Proportionality
- Corollary of proportionality theorem
- Graphing Proportions
- Proportionality
Similar Triangles with Scale Factor Slider
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1) Try moving point C around and write down what you notice. 2) Try moving the slider and write down what you notice. |
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3) Move the green triangle until point D is aligned on top of point A, and Point E is sitting on the line. 4) Now try moving point C and write down what you notice. 5) Now move the slider and write down what you notice. |
ACCESS - Triangle Proportionality
DE intersects Triangle ABC and is parallel to side AC. Drag any point on ABC to adjust the triangle. Drag D to adjust DE up or down the sides of the triangle. The text on the left provides the measure of the segments and their ratios. [br]1. Move D to change segment DE's position. What do you notice about the ratios BD/DA and BE/EC?[br]2. Adjust points A, B, and C to change the triangle. Again, move D to change segment DE's position. Does the rule about the ratios from #1 still hold?[br]3. Can you make the ratios equal 1? What can you say about segment DE when the ratio of BD/DA = 1?[br]4. What can you say about the relationship of triangle ABC to triangle DBE? Justify your answer. Will this always be true?