Tse ka Hare
Khatisong ena, re tla shebana le tlhaloso le thepa ea mantlha ea li-midlines tsa convex quadrilateral mabapi le ntlha ea bona ea litselana, kamano le diagonals, joalo-joalo.
Hlokomela: Ho latela se latelang, re tla sheba feela setšoantšo sa convex.
Boikemisetso ba moleng o bohareng oa quadrilateral
Karolo e kopanyang libaka tse bohareng tsa mahlakoreng a fapaneng a quadrilateral (ke hore, ha e li kopane) e bitsoa ea eona. mola o bohareng.
- EF – mola o bohareng o kopanyang libaka tse bohareng AB и CD; AE=EB, CF=FD.
- GH - mola o bohareng o arolang li-midpoints BC и AD; BG=GC, AH=HD.
Thepa ea moeli o bohareng oa quadrilateral
Thepa 1
Methalo e bohareng ya quadrilateral intersect le ho kgephoha ha pedi ntlheng ya mateano.
- EF и GH (mela e bohareng) kgahlano ka ntlha e le nngwe O;
- EO=OF, GO=OH.
Hlokomela: Point O is centroid (kapa barycenter) quadrilateral.
Thepa 2
Sebaka sa mateano a li-midline tsa quadrilateral ke sebaka se bohareng sa karolo e kopanyang li-midpoints tsa diagonal tsa eona.
- K – bohareng ba diagonal AC;
- L – bohareng ba diagonal BD;
- KL e feta ka ntlha O, ho kopanya K и L.
Thepa 3
Bohareng ba mahlakore a quadrilateral ke matheba a parallelogram e bitsoang Parallelogram ea Varignon.
Bohareng ba parallelogram e entsoeng ka tsela ena le ntlha ea mateano ea li-diagonals tsa eona ke bohareng ba bohareng ba karolo ea pele ea quadrilateral, ke hore ntlha ea bona ea ho kopana. O.
Hlokomela: Sebaka sa parallelogram ke halofo ea sebaka sa quadrilateral.
Thepa 4
Haeba li-angles tse pakeng tsa diagonal tsa quadrilateral le midline ea eona li lekana, joale li-diagonal li na le bolelele bo lekanang.
- EF – mola o bohareng;
- AC и BD - diagonals;
- ∠ELC = ∠BMF = a, Ka lebaka leo AC=BD.
Thepa 5
Bohareng ba quadrilateral e ka tlase kapa e lekana le halofo ea kakaretso ea mahlakore a eona a sa thulaneng (ha feela mahlakore ana a bapile).
EF – mola o mahareng o sa thulaneng le mahlakore AD и BC.
Ka mantsoe a mang, moeli o bohareng oa quadrilateral o lekana le halofo ea kakaretso ea mahlakoreng a sa kopaneng le eona haeba feela karolo e fanoeng ea quadrilateral e le trapezoid. Tabeng ena, mahlakoreng a nkiloeng ke metheo ea setšoantšo.
Thepa 6
Bakeng sa vector ea midline ea arbitrary quadrilateral, tekano e latelang e na le:
