高一（下）數(shù)學(xué)期末綜合測(cè)試一及答案-預(yù)覽頁
【正文】 只有不共線與由于 ,ee 21 ??? ??? ??? ,0k1 ,0k .1k ??? 21．解：①令 m＝ |a＋ tb|, ? ?.c o s1ac o sbatb c o saac o sbatc o sb1a2tb atc o sba2tb tc o sba2btatbam22222222222222222222???????????????????????????????????????????則 .s inam,c o sbat m i n ?????? 時(shí)當(dāng) bat 1,cos θ a 與b 共線且同向, :②證明 ?????? ? ? ,0bababbabatbab 2 ??????????? ??????? ? ?.tbab ??? ??? ??? ??? .kyy ,hxx: .22 設(shè)平移公式解 得代入 2x2y,kyy ,hxx ???? ??? ???? ? ? ,2 2hxky ????? ,kh2xh4x2y 22 ???????即 ???????? ???? .x4x2y ,kh2hx4x2y 222 x4x2kh2hx4x2 222 ??????? ? ? 0kh2x4h4x4 22 ?????? .0xx, 21 ??則由于交點(diǎn)關(guān)于原點(diǎn)對(duì)稱 .1h ,04h4 ?????即 ??????????????.x4x2y,k2x4x2y222121得 :,0yy 21 兩式相加得又由于 ?? ? ? ? ? .k2xx4xx20 212221 ?????? ,2k ??? ,x2y ,2yy ,1xx ,2yy ,1xx 2???? ??? ??????? ??? ???? 代入 .x8x2y 2 ?????故
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