如圖,在Rt△ABC中,∠ACB=90°,CD為AB邊上的高,若點(diǎn)A關(guān)于CD所在直線(xiàn)的對(duì)稱(chēng)點(diǎn)E恰好為AB的中點(diǎn),則∠B的度數(shù)是( ?。?/p>
如圖所示,CD=CA,∠1=∠2,EC=BC,求證:△ABC≌△DEC.
⑴作ABC關(guān)于直線(xiàn)MN對(duì)稱(chēng)的A1B1C1;
⑵求ABC的面積;
⑶在直線(xiàn)MN上找一點(diǎn)P,使得PA+PB最小.
如圖,在△ABC中,已知AB=AC,AD平分∠BAC,點(diǎn)M,N分別在AB,AC邊上,AM=2MB,AN=2NC.求證:DM=DN.
①在射線(xiàn)BM上作一點(diǎn)C,使AC=AB,連接AC;
②作∠ABM 的角平分線(xiàn)交AC于D點(diǎn);
③在射線(xiàn)CM上作一點(diǎn)E,使CE=CD,連接DE.