Carcass wrote:
In the coordinate geometry plane, point A is the midpoint between points (5,8) and (-3, -2). If the midpoint between point A and point B is (4, -1), in which quadrant does point B lie?
A. I
B. II
C. III
D. IV
E. None of the above
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITIONGRE - Math Book The midpoint of (a, b) and (c, d) = [(a+c)/2, (b+d)/2]Given: Point A is the midpoint between points (5,8) and (-3, -2)
So,
the coordinates of point A = [(5 + -3)/2, (8 + -2)/2] = (2/2, 6/2) =
(1, 3)Given: The midpoint between point A and point B is
(4, -1)So, we don't know the coordinates of point B
Let the coordinates of point B = (x, y)
Applying the formula, we get: [(
1 + x)/2, (
3 + y)/2] =
(4, -1)This means (
1 + x)/2 =
4Solve to get: x = 7
It also means (
3 + y)/2 =
-1Solve to get: y = -5
So, the coordinates of point B = (7, -5)
So, point B is in quadrant IV
Answer: D