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设P(x0,y0),当△ABP和△BCP无公共部分时,P在AC段。直线PB在y轴的截距是-3y0/(x0-3)
=3(x0+1),PB交y轴于H.
S△PAB=S△CHB+S△CHP
|AB| |y0| /2=|CH| |OB| /2+|CH| |x0| /2
4y0=(3-3(x0+1)) (-x0)+(3-3(x0+1))*3
-4(x0+1)(x0-3) =3(x0-3)x0
-4(x0+1)=3x0,x0=-4/7; y0=75/49;
,当△ABP和△BCP有公共部分时,直线CP在x轴的截距是-3x0/(y0-3)=3/(x0-2),交x轴于E.
因S△ABP=S△BCP,故S△PAE=S△CEB,即
|AE| |y0| /2=|BE|*3/2
|-1- 3/(x0-2)| |y0|=|3- 3/(x0-2) |*3
|x0+1)/(x0-2| |(x0+1)(x0-3)|=9*|x0-3)/(x0-2|,即
|x0+1|^2=9, (x0+1)^2=9,x0=-4,2(不合题意,故舍去),y0=-21.因此
P1(-4/7,75/49),P2(-4,-21).