Question

Point P is the midpoint of seg AB. Co­-ordinates of P are (­-1,1) and A are (4,3). What are the co-­ordinates of point B?

A) (6, 1) B) (-­6, ­1) C) (6, ­-1) D) (­-6, -1)

Answer 1

Answer:

A(4,3) and P (-1,1)

P is midpoint of  ab

Let co-ordinates of point B be (x,y).

So ,   $\frac{m}{n } = \frac{1}{1}$

P(-1,1) = $\frac{mx2 + nx1}{m+n} + \frac{my2 + ny1}{m+n}$

P(-1,1) = $\frac{4+x}{2} +\frac{y+3 }{2}$

-2 = 4+x               2 =y+3

x = -2-4                y =2-3

x = -6                   y = -1

Therefore; co-ordinates of point B = (-6,-1)

Ans:  D) (-6,-1)

Answer 2

Answer:

A(4,3) and P (-1,1)

Pis midpoint of ab

Let co-ordinates of point B be (x,y).

So, m = 1

P(-1,1)

mx2+nx1

m +n

y+3

2

=

P(-1,1) =

4+x

-2 = 4+x

X = -2-4

X = -6

my2+nyl

2 =y+3

y =2-3

y = -1

Therefore; co-ordinates of point B = (-6,-1)

Ans: D) (-6,-1)