Question

已知ab两点相距10厘米,动点p到点a的距离是它到点b的距离的3倍,求点p的轨迹

Answer 1

设P(x,y) a(0,0) b(10,0)

pa^2=x^2+y^2 pb^2=(x-10)^2+y^2

pa=3pb 所以x^2+y^2=9x^2+9y^2-180x+900

8x^2+8y^2-180x+900=0