Here,
The midpoint of segment QR is M
m(-2,9) x3=-2,y3=9
Q=(-8,12)x1=-8,y1=12
R=x2,y2
we know that,
[tex]\tt{ m=\dfrac{Q+R}{2} }[/tex] ⠀
So,
x3=[tex]\tt{\dfrac{x1+x2}{2} }[/tex] ⠀
[tex]\tt{-2=\dfrac{-8+x2}{2} }[/tex] ⠀
[tex]\tt{-2×2=-8+x2 }[/tex] ⠀
[tex]\tt{x2=8-4 }[/tex] ⠀
[tex]\tt{x2=4 }[/tex] ⠀
x2=4
now we find the y coordinate y2.
y3=[tex]\tt{\dfrac{y1+y2}{2} }[/tex] ⠀
[tex]\tt{9=\dfrac{12+y2}{2} }[/tex] ⠀
[tex]\tt{9×2=12+y2 }[/tex] ⠀
[tex]\tt{y2=18-12 }[/tex] ⠀
[tex]\tt{y2=6 }[/tex] ⠀
y2=6
Now we get the two coordinate of R
so,
R=(x2,y2)=(4,6)
