The points whose co–ordinates are x=x1+t(x2−x1), y=y1+t(y2−y1) divides the join of (x1,y1) and (x2,y2) in the ratio
t1+t
1+tt
t1−t
1−tt
x=x1+t(x2−x1),y=y+t(y2−y1)
x=(1−t)x1+tx2(1−t)+t,y=(1−t)+ty2(1−t)+t
⇒ p(x,y) divides join of A(x 1,y1) & B(x 2,y2) in the ratio t : 1−t
Ratio =t1−t