Given:
Coordinates of point C are (-3,6).
Point B(0,5.5) is the midpoint of AC.
To find:
The coordinates of A.
Solution:
Let the coordinates of point A are (a,b).
Formula for midpoint:
[tex]Midpoint=\left(\dfrac{x_1+x_2}{2},\dfrac{y_1+y_2}{2}\right)[/tex]
Using the above formula, the midpoint of A(a,b) and C(-3,6) is
[tex]B=\left(\dfrac{a+(-3)}{2},\dfrac{b+6}{2}\right)[/tex]
[tex](0,5.5)=\left(\dfrac{a-3}{2},\dfrac{b+6}{2}\right)[/tex]
On comparing both sides, we get
[tex]\dfrac{a-3}{2}=0[/tex]
[tex]a-3=0[/tex]
[tex]a=3[/tex]
and,
[tex]\dfrac{b+6}{2}=5.5[/tex]
[tex]b+6=11[/tex]
[tex]b=11-6[/tex]
[tex]b=5[/tex]
Therefore, the coordinates of point A are (3,5).
