Question

The end points of one diagonal of a rhombus are (-5,2) and (1,6). If the coordinates of the 3rd vertexare (-6,10), what are the coordinates of the 4th vertex?

A.(2,-2)
B.(-8,0)
C.(4,8)
D(-9,8)

Answer 1

Look at the picture.


`E\left((-5+1)/(2);\ (2+6)/(2)\right)\to E\left((-4)/(2);\ (8)/(2)\right)\to E(-2;\ 4)`


`\vec{BE}=[-2-(-6);\ 4-10]=[4;\ -6]`


`D(x;\ y)\\\\\vec{ED}=[x-(-2);\ y-4]=[x+2;\ y-4]\\\\\vec{ED}=\vec{BE}\ therefore\\\\ \ [x+2;\ y-4]=[4;\ -6]\to x+2=4\ and\ y-4=-6\\\\x=2\ and\ y=-2\\\\Answer:\ \boxed{A.\ (2;\ -2)}`