拋物線焦點(diǎn)弦性質(zhì)Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.一、復(fù)習(xí)⒈焦點(diǎn)弦的定義⒉焦半徑公式⒊通徑若M在焦點(diǎn)為F的拋物線上，則|MF|=OxyFMOxyH1FH2Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.OxyAFB證明？課本P119習(xí)題8.5的第7題Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.引申性質(zhì)1Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.OxyAFB分析結(jié)論Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.OxyAFB分析Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.引申性質(zhì)1性質(zhì)2Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.⒈過(guò)拋物線的焦點(diǎn)作直線交拋物線于兩點(diǎn)．若，則|AB|=___________⒉過(guò)拋物線的焦點(diǎn)作傾斜角為的弦，則此弦長(zhǎng)為_(kāi)_______；一條焦點(diǎn)弦長(zhǎng)為16，則弦所在的直線傾斜角為_(kāi)________．⒊過(guò)拋物線的對(duì)稱軸上有一點(diǎn)M(p,0)，作一條直線與拋物線交于A、B兩點(diǎn)，若A點(diǎn)縱坐標(biāo)為，則B點(diǎn)縱坐標(biāo)為_(kāi)_______例題8244pEvaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.4.若AB是拋物線的一條弦，O為坐標(biāo)原點(diǎn)，則OAOB的充要條件是弦AB過(guò)點(diǎn)（2p，0）。變：設(shè)拋物線的焦點(diǎn)為F，經(jīng)過(guò)點(diǎn)F的直線交拋物線于A、B兩點(diǎn)，點(diǎn)C在拋物線的準(zhǔn)線上，且BCx軸，證明AC經(jīng)過(guò)原點(diǎn)O。（01高考）5.過(guò)拋物線焦點(diǎn)的一條直線，與它交于P、Q兩點(diǎn)，經(jīng)過(guò)點(diǎn)P和拋物線頂點(diǎn)的直線交準(zhǔn)線于點(diǎn)M，求證直線MQ平行于拋物線的對(duì)稱軸。（課本P123習(xí)題第6題）例題Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile.Copyright2004-2011AsposePtyLtd.小結(jié)作業(yè)本節(jié)課，我們主要從代數(shù)（方程）的角度研究拋物線的焦點(diǎn)弦的一些性質(zhì)。而對(duì)于從幾何觀點(diǎn)去研究它的性質(zhì)，希望同學(xué)們課后完成。探究拋物線焦點(diǎn)弦的其它性質(zhì)Evaluationo