- Midpoint Formula: [tex](\frac{x_2+x_1}{2},\frac{y_2+y_1}{2})[/tex]
So firstly, let's start with the x-coordinates. Since we know the midpoint's x-coordinate and point A's x-coordinate, we can solve for point B's x-coordinate as such:
[tex]\frac{-1+x}{2}=0.5\\\\-1+x=1\\\\x=2[/tex]
Next, do the same thing except solve for the y-coordinate and using point A's y-coordinate and the midpoint's y-coordinate:
[tex]\frac{-9+y}{2}=-2.5\\\\-9+y=-5\\\\y=4[/tex]
Putting it together, point B's coordinates are (2,4).
