It is known that in the I and III quadrants, the signs of the x- and y- are the same.
Jackie claims that the points with the same x - and y - coordinates must lie in the I or III quadrant.
His claim is true.
The points with the same x - and y - coordinates are of the form (a,a) or (-a,-a). If the point is of the form (a,a), it lies in the quadrant I
If the point is of the form (-a,-a), it lies in quadrant III.
