高二双曲线的问题快快在线等明天要交
(1)BF=3倍根号3
AF-BF=BF-CF
AF+CF=2BF=6倍根号3
根号[x1^2+(y1-5)^2]+根号[x2^2+(y2-5)^2]=6倍根号3
y1^2/12-x1^2/13=1
y2^2/12-x2^2/13=1
根号[13/12y1^2-13+(y1-5)^2]+根号[13/12y3^2-13+(y2-5)^2]=6倍根号3
根号1/12*根号[25y1^2-120y1+144]+根号1/12*根号[25y2^2-120y2+144]=6倍根号3
根号1/12*(5y1-12)+根号1/12*(5y2-12)=6倍根号3
5y1-12+5y2-12=36
y1+y2...全部
(1)BF=3倍根号3
AF-BF=BF-CF
AF+CF=2BF=6倍根号3
根号[x1^2+(y1-5)^2]+根号[x2^2+(y2-5)^2]=6倍根号3
y1^2/12-x1^2/13=1
y2^2/12-x2^2/13=1
根号[13/12y1^2-13+(y1-5)^2]+根号[13/12y3^2-13+(y2-5)^2]=6倍根号3
根号1/12*根号[25y1^2-120y1+144]+根号1/12*根号[25y2^2-120y2+144]=6倍根号3
根号1/12*(5y1-12)+根号1/12*(5y2-12)=6倍根号3
5y1-12+5y2-12=36
y1+y2=12
(2)AC中点((x1+x2)/2,(y1+y2)/2)即((x1+x2)/2,6)
中垂线斜率为AC斜率负倒数即
(x2-x1)/(y1-y2)
Y-6=(x2-x1)/(y1-y2)[X-(x1+x2)/2]
Y-6=(x2-x1)X/(y1-y2)-(x2^2-x1^2)/2(y1-y2)
Y-6=(x2-x1)X/(y1-y2)-(y2^2-y1^2)13/24(y1-y2)
Y-6=(x2-x1)X/(y1-y2)+(y2+y1)13/24
Y-6=(x2-x1)X/(y1-y2)+13/2
Y-25/2=(x2-x1)(X-0)/(y1-y2)
过定点(0,25/2)
。
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