Ta co AC=2a
Lay M la trung diem cua AO tu do co SM vuong AO va AM=a2 ; ha SH vuong AD suy ra SH vuong (ABCD)
Tu do suy ra mp (SMH) vuong AC nen MH vuong AC
Ta co cos^MAH=cos^CAD=>AMAH=ADAC=>AH=AM.ACAD=a√3
Suy ra HD=2a√3 ma goc giua SD va day la 60o tuc la goc ^SDA=60o
Nen co dk SH=HD.tan60o=2a
De dang co the tich V=13SH.AD.AB=2a3√3
De tinh khoang cach tu SB toi AC ta dung hinh binh hanh ACBE tu day khoang cach can tim chinh la
khoang cach tu A den mp(SBE)
Goi khoang cach do la d thi d=3VSABESSEB(1)
Toi day tinh 3VASBE=32V=a3.√3
* Tinh SSEB
MH giao vs EB tai K suy ra MK vuong EB do EB song song AC tu do suy ra EB vuong vs (SKM) suy ra SK vuong EB
* Tinh SK
Co KH=EH.sin^BEH=EH.sin30o=12(AH+AE)=2a√3
Co SK=√KH2+SH2=4a√3
Tu do co SSEB=12SK.EB=4a2√3
Vay tu (1)cod=3a4