SOLUTION: the midpoint og GN is (9,11). One endpoint is N(7,5). Your friend calculates the coordinates of endpoint G as (15,13). What is his error?

Algebra ->  Geometry-proofs -> SOLUTION: the midpoint og GN is (9,11). One endpoint is N(7,5). Your friend calculates the coordinates of endpoint G as (15,13). What is his error?      Log On


   

Question 1049156: the midpoint og GN is (9,11). One endpoint is N(7,5). Your friend calculates the coordinates of endpoint G as (15,13). What is his error?
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
G is some unknown endpoint, G(x,y).

Midpoint for GN will need to fit %287%2Bx%29%2F2=9, and %285%2By%29%2F2=11.

Solve for x and y.

7+x=18
x=18-7
x=11
-
y+5=22
y=22-5
y=17
-
Correct way to get the point G(11,17) but did not uncover the friend's mistake.

The only common trouble I can see is that the coordinates (15,13) are each four off but in different directions. My only guess is that friend mistakenly added or subtracted 4 to each x & y result.