Moi nguoi vao giai cau b giup voi.minh bi cau b ruj.?

Rat cam on cau tra loi cua ban Ha.nhung tiec la ban lam sai roi. tam giac SAC khong the vg tai A duoc. vi ta co :

tam giac ABD deu va SA=SB=SD ==> hinh chop S.ABD deu. Goi G la tam cua tam giac ABD ==> SG _|_ (ABD) ==> SG _|_ AC ==> SA khong the vg voi AC duoc.

O cau nay minh biet chac chan la tam giac SAC vuong goc tai S.nhung khong the nao,chung minh duoc.mong moi nguoi giup cho.thanks

a. AC giao BD tai O

SB=SD=>SBD cân

SO vg BD + AC vg BD=BD vg (SAC)

(SAC)giao (ABCD)={AC}=> (SAC)vg(ABCD)

b. (SAC)vg(ABCD)=>AC vg SA=SAC vg A

c. Sorry minh chua lm ra. No lquan den BDA= 60. Minh dot sin cos lm