toan thi vao 10 kho

U

utan1995

Co le minh se chung minh tu giac MADB la tu giac noi tiep => goc BMD = goc BAD
=> BMD = 60*
 
J

jet_nguyen

[tex] \triangle PBC \sim \triangle CDN (g.g) [/tex]

=> [tex]\frac{BP}{a} = \frac{a}{ND} => \frac{BP}{BD}=\frac{BD}{ND}[/tex] (a là dộ dài cạnh hình thoi)

=> [tex]\triangle BPD \sim \triangle BDN (c.g.c)[/tex]

=> [tex] \hat{MBP}+\hat{BMD} = \hat{BPD} = \hat{NBD} = \hat{MBP}+\hat{ABD}[/tex]

=> [tex]\hat{BMD} = \hat{ABD} = {60}^{0}[/tex]
 
V

venus01

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