Question

【題目】如圖所示，已知△ABC和直線MN．求作：△A′B′C，使△A′B′C和△ABC關(guān)于直線MN對(duì)稱．（不要求寫作法，只保留作圖痕跡）

Answer 1

【答案】作圖見解析.

【解析】

試題分析：要作出一個(gè)三角形關(guān)于直線對(duì)稱,只需要作出三個(gè)頂點(diǎn)關(guān)于這條直線的對(duì)稱點(diǎn),然后連接這三個(gè)對(duì)稱點(diǎn)即可,如圖,過(guò)點(diǎn)A作MN的垂線交MN與點(diǎn)K,延長(zhǎng)AK至點(diǎn)A′,使得AK= A′K, 點(diǎn)A′是點(diǎn)A關(guān)于MN的對(duì)稱點(diǎn), 過(guò)點(diǎn)B作MN的垂線交MN與點(diǎn)L,延長(zhǎng)BL至點(diǎn)B′,使得BL= B′L, 點(diǎn)B′是點(diǎn)B關(guān)于MN的對(duì)稱點(diǎn), 點(diǎn)C關(guān)于MN的對(duì)稱點(diǎn)就是點(diǎn)C,連接A′B′C,得到圖形△A′B′C.

試題解析：如圖,過(guò)點(diǎn)A作MN的垂線交MN與點(diǎn)K,延長(zhǎng)AK至點(diǎn)A′,使得AK= A′K, 點(diǎn)A′是點(diǎn)A關(guān)于MN的對(duì)稱點(diǎn), 過(guò)點(diǎn)B作MN的垂線交MN與點(diǎn)L,延長(zhǎng)BL至點(diǎn)B′,使得BL= B′L, 點(diǎn)B′是點(diǎn)B關(guān)于MN的對(duì)稱點(diǎn), 點(diǎn)C關(guān)于MN的對(duì)稱點(diǎn)就是點(diǎn)C,連接A′B′C,得到圖形△A′B′C.