Three points are given:
(a1,b1), (a2,b2), and (a1+a2,b1+b2)
These points are collinear, meaning they lie on the same straight line.
For three points to be collinear, the slope between any two pairs of points must be equal.
Finding the slope between (a1,b1) and (a1+a2,b1+b2):
Slope =(a1+a2)−a1(b1+b2)−b1
Slope =a2b2
Finding the slope between (a2,b2) and (a1+a2,b1+b2):
Slope =(a1+a2)−a2(b1+b2)−b2
Slope =a1b1
Since the points are collinear, the slopes must be equal:
a2b2=a1b1
Cross-multiplying:
a1b2=a2b1
Therefore, the required condition is a1b2=a2b1.