Question

 Cho tu giac ABCD co goc A= 2gocB. gocB=4gocC,D=goc B +20 do . Tinh so do cac goc 

 

Answer 1

Có: `\hat{B}=4\hat{C}=>\hat{C}=1/4\hat{B}`

Xét t/g `ABCD` có: `\hat{A}+\hat{B}+\hat{C}+\hat{D}=360^o`

  `=>2\hat{B}+\hat{B}+1/4\hat{B}+\hat{B}+20^o=360^o`

  `=>17/4\hat{B}=340^o`

  `=>\hat{B}=80^o`

    `->{(\hat{A}=2.80^o =160^o ),(\hat{C}=1/4 .80^o =20^o ),(\hat{D}=80^o +20^o =100^o):}`