Question

Tìm số đo góc B, D trong hình sau:(hơi xấu)

Answer 1

Ta có: \(\widehat{B}+\widehat{D}+\widehat{C}+\widehat{A}=360^0\)

\(\Rightarrow\widehat{B}+\widehat{D}=360^0-90^0-150^0=120^0\)

\(\Rightarrow3x=120^0\Rightarrow x=40^0\)

\(\Rightarrow\left\{{}\begin{matrix}\widehat{B}=2x-2.40^0=80^0\\\widehat{D}=x=40^0\end{matrix}\right.\)

Answer 2

Trong hình thang ABCD có:

 \(\widehat{A}+\widehat{B}+\widehat{C}+\widehat{D}=360^o\)

\(\Rightarrow90^o+2x+150^o+x=360^o\)

\(\Rightarrow240^o+3x=360^o\)

\(\Rightarrow3x=120^o\)

\(\Rightarrow x=40^o\)

\(\Rightarrow\left\{{}\begin{matrix}\widehat{B}=40^o.2=80^o\\\widehat{D}=40^o\end{matrix}\right.\)