Lub plaub fab uas tsim los ntawm kev koom nrog cov midpoints sib law liag ntawm ib lub plaub fab uas nws kab pheeb ces kaum yog congruent yog a rhombus.
Thaum qhov nruab nrab ntawm qhov chaw nyob ib sab ntawm plaub fab txuas nrog ntu?
Thaum cov ntsiab lus nruab nrab ntawm sab uas nyob ib sab ntawm quadrilateral txuas los ntawm ntu. Cov ntu no daim ntawv a parallelogram. Cov ntu no tsim parallelogram tsis hais txog hom plaub fab. Txij li txhua sab ntawm cov ntu no yog qhov sib txawv ntawm ib leeg.
Yuav ua li cas quadrilateral yog tsim thaum nruab nrab ntawm ib sab ntawm quadrilateral koom?
Cov plaub plaub uas tsim los ntawm kev koom nrog cov ntsiab lus nruab nrab ntawm ob sab ntawm plaub plaub fab, coj mus rau hauv kev txiav txim, yog ib qho parallelogram. (A) PQRS yog ib daim duab plaub (B) PQRS yog parallelogram (C) kab pheeb ces kaum ntawm PQRS yog perpendicular (D) kab pheeb ces kaum ntawm PQRS yog sib npaug.
Thaum lub midpoints ntawm ob sab ntawm ib quadrilateral txuas nrog lub quadrilateral tshiab yog ib qho parallelogram?
Lub midpoints ntawm ob sab ntawm ib tug arbitrary quadrilateral tsim ib tug parallelogram. Yog hais tias lub quadrilateral yog convex los yog concave (tsis complex), ces cheeb tsam ntawm lub parallelogram yog ib nrab ntawm lub quadrilateral.
Yuav ua li cas daim duab yog tsim los ntawm kev koom nrog cov midpoints ntawm cov nyob ib sab ntawm ib parallelogram?
Thiab thaum peb txuas qhov nruab nrab ntawm plaub sab rau lwm qhovgeometrical shape yuav raug tsim uas muaj tib yam khoom ntawm ib qho parallelogram vim qhov xwm txheej geometrical symmetry. Vim li no, cov duab geometrical tshiab yuav yog parallelogram.
