Question

given that two vertices of a triangle are at (-7,-3) and (-4,8) and the centroid is at (-1,3) find

I) the coordinates of the third vertex

ii) the coordinates of the orthocentre

Answer 1

see the attachment for the solution.

Answer 2

(-1,3)=((-7-4+x)/3,(-3+8+y)/3)
hence we can equate the x coordinates and y coordinates
-1=(-11+x)/3                           3=(5+y)/3
-3=-11+x                                 9=5+y
x=-3+11                                  y=4
x=8
                        (x,y)=(8,4)