Investigating Geometry: Similarity

Henrico County Public Schools


Algebraic Review
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May 2006

Lesson 5-2: Exploring Similar Polygons


SOL G.14: The student will use similar geometric objects in two--dimensions to (a) compare ratios between side lengths and perimeters.

 Applet Directions 1 Close 
  1. Construct a quadrilateral similar to Quadrilateral ABCD so that the scale factor of Quadrilateral ABCD to your quadrilateral is 2:1.

  2. Hint: Use the dilation point E and the rays provided to "frame" your costruction.

  3. Move points A, B, C, D, and E. How do they effect your quadrilateral?

  Hands-On Activities Close 
  1. Ad Infinitum (pdf)
  2. Solid Gold (pdf)
  Other Web Sites Close 
  1. Glencoe: On Line Quiz
  2. Similar Figures: This is a four step process: Steps 1 through 3 are similar to a textbook while step 4 is an online multiple choice "quiz" with instant feedback.
 Puzzle & Problems tangram Close 

A parallelogram with sides 4 centimeters and 8 centimeters long is projected onto a screen. The ratio between a 4 cm side and its projection is 2:17.
a. What is the measurement of the longer side of the parallelogram as it is projected on the screen?
b. If you move the projector, the measurement of the shorter side of the parallelogram becomes 30 cm. What is the new scale factor?