Yuav ua li cas muaj pes tsawg tus ntug polyhedron uas muaj plaub lub ntsej muag thiab plaub vertices?
Yuav ua li cas muaj pes tsawg tus ntug polyhedron uas muaj plaub lub ntsej muag thiab plaub vertices?

Video: Yuav ua li cas muaj pes tsawg tus ntug polyhedron uas muaj plaub lub ntsej muag thiab plaub vertices?

Video: Yuav ua li cas muaj pes tsawg tus ntug polyhedron uas muaj plaub lub ntsej muag thiab plaub vertices?
Video: yuav coj li cas kom luag nyiam 2024, Kaum ib hlis
Anonim

Yog hais tias cov khoom yog polyhedron, npe nws thiab nrhiav tus naj npawb ntawm lub ntsej muag, ntug thiab vertices nws muaj. Lub hauv paus yog daim duab peb sab thiab txhua sab yog daim duab peb sab, yog li qhov no yog daim duab peb sab pyramid, uas tseem hu ua tetrahedron. Muaj 4 lub ntsej muag, 6 ntug thiab 4 kab.

Ua kom pom qhov no, pes tsawg lub ntsej muag thiab cov npoo puas muaj polyhedron?

Lub polyhedron no muaj 12 lub ntsej muag, 20 rov , thiab 30 ntug.

Lub pyramid nrog 4 lub ntsej muag hu ua dab tsi? Lub tetrahedron yog ib hom pyramid , uas yog ib tug polyhedron nrog lub tiaj polygon puag thiab daim duab peb sab ntsej muag txuas lub hauv paus mus rau ib qho kev taw qhia. Nyob rau hauv cov ntaub ntawv ntawm tetrahedron lub hauv paus yog daim duab peb sab (ib yam ntawm plaub lub ntsej muag tuaj yeem suav hais tias yog lub hauv paus), yog li tetrahedron tseem hu ua "daim duab peb sab pyramid ".

Ua raws li qhov no hauv kev txiav txim siab, puas muaj polyhedron muaj 4 lub ntsej muag?

Hauv geometry, a polyhedron yog ib qho khoom hauv peb qhov loj me nrog lub tiaj ntsej muag thiab cov npoo ncaj. Txhua ntug muaj raws nraim ob ntsej muag , thiab txhua vertex yog surrounded los ntawm alternating ntsej muag thiab ntug. Qhov tsawg tshaj plaws polyhedron yog tetrahedron nrog 4 daim duab peb sab ntsej muag ,, 6 yuv 4 ntsug.

Puas muaj polyhedron muaj 20 lub ntsej muag 40 npoo thiab 30 ntsug?

Tsis yog, as 20 + 30 - 40 tsis sib npaug 2. yog li tsis muaj polygon nrog 20 fim , 40 ntug thiab 30 vertices.

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