1.上課時(shí),老師要求同學(xué)們解決下面這道問(wèn)題:
(1)問(wèn)題1:如圖(a),矩形ABCD中,AB=6,AD=10,點(diǎn)E在邊CD上,將△ADE沿AE翻折,點(diǎn)D剛好落到邊BC上的點(diǎn)F處.
①CF的長(zhǎng)為
;
②求DE的長(zhǎng).
請(qǐng)你也完成這道問(wèn)題.
完成問(wèn)題1后,老師進(jìn)行了如下的變式:
(2)問(wèn)題2:如圖(b),矩形ABCD中,AB=6,AD=10,若E為邊CD的中點(diǎn),將△ADE沿AE翻折到△AD′E,延長(zhǎng)AD′交BC于點(diǎn)M,△ABM的周長(zhǎng)是多少?請(qǐng)你直接寫(xiě)出答案.
(3)問(wèn)題3:如圖(c),將矩形變?yōu)檫呴L(zhǎng)為6的正方形ABCD,點(diǎn)E在邊CD上,DE=4,將△ADE沿AE翻折到△AD′E,延長(zhǎng)AD′交BC于點(diǎn)N,請(qǐng)你直接寫(xiě)出BN的長(zhǎng).