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Topic: Geometry Question #3
Replies: 39   Last Post: Jun 18, 2009 5:05 PM

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 BHowitt@wlsv.org Posts: 47 Registered: 9/11/06
RE: Geometry Question #3
Posted: Jun 17, 2009 2:36 PM
 att1.html (4.9 K)

Because SED says so and that is the final answer. They are the all
knowing.

Beth Howitt
Math Department
Wellsville High School

"edward mertson" <emertson@nvcs.stier.org>
Sent by: owner-nyshsmath@mathforum.org
06/17/2009 01:59 PM
nyshsmath@mathforum.org

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RE: Geometry Question #3

And in the same line of reasoning, we?ve assumed that triangle ABC is
congruent to A?B?C? yet it isn?t marked as such in the question. So is
it even a rotation?
If the question is asking if there exists a transformation that will
produce image A?B?C?, and we must assume some basic common sense
conditions (such as the 2 triangles are congruent because they look
congruent, the triangles exist in the same plane, etc?) then, after
examining the diagram, is it reasonable for a student to also assume that
it appears that the that the image is a dilation with a factor of -1?
If not, why not?

From: owner-nyshsmath@mathforum.org [mailto:owner-nyshsmath@mathforum.org]
On Behalf Of George Reuter
Sent: Wednesday, June 17, 2009 8:12 AM
To: nyshsmath@mathforum.org
Subject: RE: Geometry Question #3

Hi all,

I'm just wondering... have we assumed that the rotation was 180 degrees?
If the rotation was 181 degrees or 179 degrees, then a dilation of factor
-1 is an incorrect choice.

The picture could be interpreted as a dilation, but it must be interpreted
as a rotation.

Regards,
George Reuter

Geometry Question #3: We had students identify the transformation as a
dilation (of -1). I called the State to see if they would allow credit if
a student chose choice #2 dilation. Their response: "No because there
are too many assumptions that must be made." And they wanted proof that a
rotation of 180 degrees is the same as a dilation of -1. Apparently this
is not common knowledge in the math world. Very frustrating.....very
frustrating.....

Ed Mertson

Newark Valley High School

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