Question

The midpoint of AB is M(6,1). If the coordinates of A are (4,8), what are the coordinates of B?

Answer 1

Midpoint : (6,1)

Point A : (4,8)

Point B (xb,by)

Midpoint (xm, my)=( x1+x2) /2 , ( y1+y2)/2

So:

xm= 6 = (4+xb) /2

6 = (4+xb) /2

Solve for xb

6 x 2 = 4+ xb

12 = 4+xb

12-4 = xb

8 = xb

For Yb:

my= 1 = (8+yb) /2

1 = (8+yb) /2

Solve for yb

1(2) = 8+yb

2 = 8+ yb

2-8 = yb

-6 = yb

Coordinate of B = (xb,yb) = (8,-6)