SOLUTION: Find coordinate of missing endpoint if e is midpoint of df f(2,9) e(-1,6)

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Question 985976: Find coordinate of missing endpoint if e is midpoint of df
f(2,9) e(-1,6)
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
Hi there,
Using vectors
DE = EF
e - d = f - e
Collect like terms
-d = f - 2e
Multiply both sides by -1
d = 2e - f
d = 2(-1,6) - (2,9)
d = (-2,12) - (2,9)
d = (-4,3)
This is the missing endpoint.
Hope this helps :-)