To find the coordinate of the point D, we can use the Midpoint point of a line Segment formula. Calculation of the formula are as follows,
Given two points A(x1,y1) and C(x2,y2), we need to locate the midpoint coordinate of this line denoted as B(x,y).
To solve for the value of x and y, we get,
x=(x1+x2)/2 and y=(y1+y2)/2
For the given problem, we need to solve first the midpoint coordinate of AC which is B.
So, A(-9,-4)=A(x1,y1) and C(-1,6)=C(x2,y2)
Hence,
B(x,y)=B((-9+(-1))/2, (-4+6)/2)=B(-10/2,2/2)=B(-5,1)
Now, since the midpoint is given but one point in the line is missing. To solve for the missing point D(x2,y2), we need to use the Midpoint Segment Formula.
That is, B(-5,1)=B(x,y) and E(-4,-3)=E(x1,y1)
So,
x=(x1+x2)/2 and y=(y1+y2)/2
-5=(-4+x2)/2 and 1=(-3+y2)/2
By Cross Multiplication and Transposing method,
-5(2)=-4+x2 and 1(2)=-3+y2
x2=-10+4=-6 and y2=3+2=5
Thus, the coordinate of D is D(-6,5).