Question

cho tam giac ABC co goc A=100

a)Tinh tong B+C

b)Ve cac tia pha giac cua B va C cat nhau tai diem M

Tinh so do goc BMC

Answer 1

a ) Xét \(\Delta ABC\) có : 

\(\widehat{A}+\widehat{B}+\widehat{C}=180^0\)

Mà : \(\widehat{A}=100^0\)

\(\Rightarrow\widehat{B}+\widehat{C}=100^0\)

b ) Ta có : \(\widehat{B}+\widehat{C}=100^0\)

\(\Rightarrow\frac{1}{2}\widehat{B}+\frac{1}{2}\widehat{C}=50^0\)

\(\Rightarrow\widehat{MBC}+\widehat{MCB}=50^0\)

Xét \(\Delta BMC\) ta có :

\(\widehat{MBC}+\widehat{MCB}=50^0\)

\(\Rightarrow\widehat{BMC}=180^0-50^0=130^0\)