If the vertex of an equilateral triangle is the origin and side opposite to it has the equation x+y=1, then the orthocentre of the triangle is
For equilateral triangle,
Centroid, orthocentre, circumcentre and incentre all coincides, at one point
So, orthocentre(centroid) of ΔABC=(x1+x2+x33,y1+y2+y33)
=⎛⎜ ⎜ ⎜ ⎜ ⎜⎝11+√3+√31+√33,√31+√3+11+√33⎞⎟ ⎟ ⎟ ⎟ ⎟⎠
=(13,13)