Question

tứ giac ABCD co A=105 độ, B=130 độ: C-D=25 độ tính c, d

Answer 1

Xét tứ giác ABCD có:

\(\widehat{C}+\widehat{D}=360^0-\widehat{A}-\widehat{B}=125^0\)

\(\Rightarrow\left\{{}\begin{matrix}\widehat{C}=\left(125^0+25^0\right):2=75^0\\\widehat{D}=\left(125^0-25^0\right):2=50^0\end{matrix}\right.\)

Answer 2

\(\left\{{}\begin{matrix}\widehat{C}+\widehat{D}=125^0\\\widehat{C}-\widehat{D}=25^0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\widehat{C}=75^0\\\widehat{D}=50^0\end{matrix}\right.\)