M = ( (x1 + x2) / 2 , (y1 + y2) / 2 )
(9, 0) = ( (x1 + 12) / 2 , (y1 + 3) / 2)
Break up this formula into two equations.
(x1 + 12) / 2 = 9 and (y1 + 3) / 2 = 0
Solve for x1 and y1 from the equations.
another way to explain it
the formula for finding the midpoint of a segment given the coordinates of its endpoints is:
((x1+ x2)/2, (y1 + y2)/2 {Average of the x coordinates, average of the y coordinates}.
For this problem we know the coordinates of the midpoint along with one of the endpoints.
So the x coordinate of the midpoint (9) must equal (12 + x2)/2.
That is: 9 = (12 + x2)/2 Solve for x2. Follow a similar pattern to find the y coordinate of the unknown endpoint.
and another way
The x's are 3 apart and the y's are 3 apart. The other endpoint is (9 - 3, 0 - 3), or (6,-3).
hope this helped you have a good day this was ez
