Question

Given the points A (-1,2) and B (7, 14), find the coordinates of the point P on directed line segment AB that partitions AB in the ratio 1:3.

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Answer 1

Now despite what you may believe, 1:3 is not 1/3 in this situation. In this case, it means "1 equal part to 3 equal parts", which is a total of 4 equal parts. In short, this question is to place point P 1/4 the distance from A to B.

Firstly, how far apart is -1 from 7 (the x-coordinates)? That would be 8 units. Multiply 1/4 by 8:

Next, how far apart is 2 from 8 (the y-coordinates)? That would be 6 units. Multiply 1/4 by 6:

Next, since from -1 to 7 you are increasing, add 2 to -1:

1 is your x-coordinate

Next, since from 2 to 8 you are increasing, add 3/2 to 2:

7/2 is your y-coordinate.

Putting it together, your answer is A. (1, 7/2)

Explanation: