Question

find the 3rd vertex of a triangle if two of its vertices are (-1,4) and (5,2) and centroid is (0,-3)

Answer 1

x1+x2+X3     = 0 
      3

-1+5+x        = 0
    3
4+x      =0
3     


4+x =  0x3
4+x =0
x= -4
do the same for "y" also
ie:

y1+y2+y3     =-3
     3

4+2+y      = -3
  3
6+y      = -3
  3

y  =  (-3x3)-6
y=15