Look I found the Orthocentre for a triangle whose vertices have the coordinates (xi,yi) where i=1,2,3
As this is inscribed in the circle... So this circle's centre must be the circumcentre of the triangle which is (0,0). Now centroid of this triangle ... u can get by the formula. So now we use 2:1 division to find Orthocentre of this triangle.
We have to find the line segment joining this Orthocentre to the centroid of the triangle formed by (xi,yi) where i=4,5,6 ( the remaining triangle I mean)... Now we find this centroid.