Answer:
The coordinates of B is (4,1)
Step-by-step explanation:
You can use the formula of mid-point. It is given that the midpoint of AB is (4,5). So you have to substitute the coordinates of A into the formula :
[tex]m = ( \frac{x1 + x2}{2} , \frac{y1 + y2}{2} )[/tex]
Let M be (4,5),
Let (x1,y1) be A(4,9),
Let (x2,y2) be B coordinates,
[tex](4 ,5) = ( \frac{4 + x}{ 2} , \frac{9 + y}{2} )[/tex]
Then you could solve it :
[tex] \frac{4 + x}{2} = 4[/tex]
[tex]4 + x = 8[/tex]
[tex]x = 4[/tex]
[tex] \frac{9 + y}{2} = 5[/tex]
[tex]y + 9 = 10[/tex]
[tex]y = 1[/tex]
