
Re: [mathlearn] Re: Question about unknown angle in a Parallelogram.
Posted:
Oct 11, 2011 9:23 AM



EVERY parallelogram has angles X, X, and 180X. 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 mathlearn@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 >>> >> >> >> >> [Nontext portions of this message have been removed] >> > > > > >  > > Yahoo! Groups Links > > >
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/>

