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Topic: [math-learn] Question about unknown angle in a Parallelogram.
Replies: 8   Last Post: Oct 11, 2011 9:59 AM

 Messages: [ Previous | Next ]
 Ralph A. Raimi Posts: 724 Registered: 12/3/04
Re: [math-learn] Re: Question about unknown angle in a Parallelogram.
Posted: Oct 11, 2011 9:23 AM
 att1.html (13.8 K)

EVERY parallelogram has angles X, X, and 180-X. If the angles
marked X are opposite each other you have no way of knowing their size.
If the angles of size X are adjacent, the parallelogram is a rectangle.

Best leave the algebra out of it; look at the picture, and use the
theorems about parallel lines cutting a transversal.

On Tue, 11 Oct 2011, jjaywilson2004 wrote:

> Okay... then how would I solve for the unknown?
>
> Jon
>
> --- In math-learn@yahoogroups.com, Ze'ev Wurman <zeev@...> wrote:

>>
>> Exterior angle theorem does not apply to quadrangles ...
>>
>> On 10/10/2011 7:42 PM, jjaywilson2004 wrote:

>>>
>>> Okay... This has me stumped!
>>>
>>> I have a Parallelogram constructed from 4 intersecting lines, with the
>>> following internal angles: X, X and (180 - X)
>>>
>>> The angle opposite (180 - X) is not given.
>>>
>>> Since I can employ Corresponding, Alternate Interior and Exterior
>>> angles to this figure, is it safe to assume I could employ the
>>> "Exterior Angle Theorem" to produce:
>>>
>>> (180 - X) = 2X
>>>
>>> Thus... giving me X = 60 degrees?
>>>
>>> Thoughts?
>>>
>>> Jon
>>>

>>
>>
>>
>> [Non-text portions of this message have been removed]
>>

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Ralph A. Raimi Tel. 585 275 4429 or (home) 585 244 9368
Dept. of Mathematics, Univ. of Rochester, Rochester, NY 14627
<http://www.math.rochester.edu/people/faculty/rarm/>

Date Subject Author
10/10/11 Jon Wilson
10/10/11 Zeev Wurman
10/10/11 Jon Wilson
10/10/11 Zeev Wurman
10/11/11 Jon Wilson
10/11/11 Zeev Wurman
10/11/11 Jon Wilson
10/11/11 Ralph A. Raimi
10/11/11 John Clement