\(a,\left\{{}\begin{matrix}AB=CD\\\widehat{A_1}=\widehat{C_1}\\AC\text{ chung}\end{matrix}\right.\Rightarrow\Delta ABC=\Delta CDA\left(c.g.c\right)\\ b,\Delta ABC=\Delta CDA\\ \Leftrightarrow\widehat{A_2}=\widehat{C_2}\\ \text{Mà 2 góc này ở vị trí so le trong }\Leftrightarrow AD\text{//}BC\\ c,\Delta ABC=\Delta CDA\\ \Leftrightarrow\widehat{D}=\widehat{B}=60^0\\ \Leftrightarrow\widehat{A_2}=180^0-\widehat{D}-\widehat{C_1}=180^0-60^0-45^0=75^0\)
Đúng 0
Bình luận (0)
