Lub tswv yim ntawm "central symmetry" ntawm daim duab qhia txog qhov muaj nyob ntawm qee qhov taw tes - qhov nruab nrab ntawm symmetry. Ntawm ob sab ntawm nws yog cov ntsiab lus ntawm daim duab no. Txhua tus yog symmetrical rau nws tus kheej.
Nws yuav tsum tau hais tias lub tswv yim ntawm qhov chaw tsis muaj nyob hauv Euclidean geometry. Ntxiv mus, nyob rau hauv phau ntawv thib kaum ib, nyob rau hauv peb caug-yim kab lus, muaj ib tug txhais ntawm ib tug spatial symmetrical axis. Lub tswv yim ntawm qhov chaw thawj zaug tshwm sim nyob rau hauv lub xyoo pua 16th.
Central symmetry yog tam sim no nyob rau hauv xws li cov paub zoo xws li ib tug parallelogram thiab ib lub voj voog. Ob tus thawj thiab thib ob daim duab muaj tib qhov chaw. Qhov nruab nrab ntawm symmetry ntawm parallelogram yog nyob rau ntawm qhov chaw ntawm kev sib tshuam ntawm cov kab ncaj nraim tawm ntawm cov ntsiab lus opposite; nyob rau hauv ib lub voj voog yog qhov chaw ntawm nws tus kheej. Ib txoj kab ncaj nraim yog tus cwj pwm los ntawm qhov muaj tus lej tsis kawg ntawm cov ntu no. Txhua qhov ntawm nws cov ntsiab lus tuaj yeem yog qhov chaw ntawm symmetry. Ib txoj cai parallelepiped muaj cuaj dav hlau. Ntawm tag nrho cov dav hlau symmetrical, peb yog perpendicular rau cov npoo. Lwm rau ntawm lub diagonals ntawm lub ntsej muag. Txawm li cas los xij, muaj ib daim duab uas tsis muaj nws. Nws yog daim duab peb sab arbitrary.
Nyob hauv qee qhov chaw, lub tswvyim"central symmetry" txhais raws li hauv qab no: lub cev geometric (daim duab) yog suav tias yog symmetrical nrog rau qhov chaw C yog tias txhua qhov A ntawm lub cev muaj qhov taw tes E nyob rau hauv tib daim duab, xws li ntu AE, dhau ntawm qhov chaw C, muab faib ib nrab ntawm nws. Muaj cov ntu sib npaug rau cov khub sib txuas ntawm cov ntsiab lus.
Cov kaum sib raug zoo ntawm ob lub halves ntawm daim duab, nyob rau hauv uas muaj lub hauv paus symmetry, kuj sib npaug. Ob daim duab dag ntawm ob sab ntawm lub hauv paus ntsiab lus, nyob rau hauv cov ntaub ntawv no, yuav superimposed rau ib leeg. Txawm li cas los xij, nws yuav tsum tau hais tias qhov kev txiav txim yog nqa tawm hauv txoj kev tshwj xeeb. Tsis zoo li daim iav symmetry, central symmetry yuav tig ib feem ntawm daim duab ib puas thiab yim caum degrees nyob ib ncig ntawm qhov chaw. Yog li, ib feem yuav sawv hauv daim iav txoj hauj lwm txheeb ze rau qhov thib ob. Qhov ob feem ntawm daim duab tuaj yeem muab tso rau ntawm ib leeg yam tsis tau coj lawv tawm ntawm lub dav hlau.
Nyob hauv algebra, khib thiab txawm ua haujlwm tau kawm siv cov duab. Rau ib qho kev ua haujlwm sib luag, daim duab tau tsim symmetrically nrog rau kev sib koom tes axis. Rau qhov kev ua haujlwm khib, nws yog txheeb ze rau lub ntsiab lus ntawm keeb kwm, uas yog, O. Yog li, rau qhov kev ua haujlwm khib, lub hauv paus symmetry yog qhov tshwm sim, thiab rau ib qho kev ua haujlwm, nws yog axial.
Central symmetry txhais tau hais tias lub dav hlau daim duab muaj qhov kev txiav txim thib ob symmetry axis. Hauv qhov no, lub axis yuav nyob rau ntawm lub dav hlau.
Central symmetry yog qhov sib xws. Ntawm ntau hom ntawv hauv kev nplua nuj, koj tuaj yeem pom qhov zoo tshaj plawscov qauv. Cov qauv zoo nkauj no suav nrog ntau hom nroj tsuag, mollusks, kab, thiab ntau yam tsiaj. Ib tug neeg qhuas lub ntxim nyiam ntawm tus kheej paj, paj, nws xav tsis thoob los ntawm kev tsim kho zoo tshaj plaws ntawm honeycombs, kev npaj cov noob rau ntawm lub kaus mom paj noob hlis, tawm ntawm cov qia cog. Central symmetry yog ubiquitous nyob rau hauv lub neej.
