①當(dāng)點(diǎn)E與點(diǎn)F重合時(shí),的長(zhǎng)為.
②當(dāng)點(diǎn)E與點(diǎn)C重合時(shí),的長(zhǎng)為.
①當(dāng)點(diǎn)F移動(dòng)到的邊上時(shí),求點(diǎn)P坐標(biāo);
②M為中點(diǎn),N為中點(diǎn),連接、 . 請(qǐng)利用備用圖探究,直接寫出在點(diǎn)P的運(yùn)動(dòng)過程中,周長(zhǎng)的最小值和此時(shí)點(diǎn)P的坐標(biāo).