How do you prove that polygons are similar?

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Discus: SAT/ACT Tests and Test Preparation: October 2003 Archive: How do you prove that polygons are similar?
 By Klmdf2 (Klmdf2) on Friday, October 03, 2003 - 01:23 pm: Edit

polygons that are not triangles, but specifically quadrilaterals, and then n-gons ?(n>4)

Just knowing that the angles are congruent is not enough.

 By Billiam2 (Billiam2) on Friday, October 03, 2003 - 01:35 pm: Edit

x

 By Klmdf2 (Klmdf2) on Friday, October 03, 2003 - 01:37 pm: Edit

the reason im asking is i had this problem:

I took a rectangle
A____________B
|...................|
|...................|
|...................|
F|------------|E
|...................|
|...................|
|____________|
D C

(C is on bottom right corner)
and c onnected the midpoints like in the diagram. So ABEF == CDFE. But if I move FE up , then everything is changed, and they are no longer similar. Cause AB/CD should = EC/BE, but they are not, since AB/CD = 1, and CE>BE when FE is moved up from the diagram. So what are the methods to prove that polygons, specifically quadrilaterals first, and then more sides, are similar, and then congruent?

Thanks.

 By Xiggi (Xiggi) on Friday, October 03, 2003 - 04:41 pm: Edit

Similar Polygons: Two polygons containing vertices that can be paired so that the corresponding angles are congruent and the corresponding sides are in proportion.

 By Klmdf2 (Klmdf2) on Friday, October 03, 2003 - 05:56 pm: Edit

i am aware of what the definition of 'similar' is. I am trying to prove that two polygons are similar w/out knowing all of their sides. My question is how do I do this.

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