If P(x, y) is any point on the line joining the points (a, 0) and (0, b) then the value ofxa+yb
Since the given points are collinear, they do not form a
triangle, which means area of the triangle is Zero.
Area of a triangle with vertices (x1,y1) ; (x2,y2) and (x3,y3) is ∣∣∣x1(y2−y3)+x2(y3−y1)+x3(y1−y2)2∣∣∣
Hence, substituting the points (x1,y1)=(a,0) ; (x2,y2)=(x,y) and (x3,y3)=(0,b)
in the area formula, we get
∣∣∣a(y−b)+x(b−0)+0(0−y)2∣∣∣=0
=>ay−ab+bx=0
Dividing by ab both sides, we get
=>xa+yb=1