Coordinates

[Marisa]

If A and B are positive, what are the coordinates of the midpoint of line segment CD on the XY plane?

1. coordinates of c (a, 1-b)
2. coordinates of d (1-a, b)

Does this follow the rule that mirrored coordinates bisect each other?

[Ian Stewart]

If A and B are positive, what are the coordinates of the midpoint of line segment CD on the XY plane?

1. coordinates of c (a, 1-b)
2. coordinates of d (1-a, b)

Does this follow the rule that mirrored coordinates bisect each other?

To find the midpoint of the line segment connecting any two points, you can simply average their x co-ordinates, and average their y co-ordinates. So in the above, the x co-ordinate of the midpoint will be:

[a + (1-a)]/2 = 1/2

and the y co-ordinate will be:

[(1-b) + b]/2 = 1/2

So the statements combined are sufficient - C.