Electric fields due to different kinds of plates

We have a triangular uniformly charged plate of charge density $\sigma$.

We take a point just above a vertex of the triangular plate at a distance $d$ perpendicular to the plane of the triangle. Let the vertical component of electric field at that point be $E(d)$ in $V/m$

Find $\displaystyle \lim_{d \rightarrow 0}{E(d)}$

Details and Assumptions:

1) $\sigma = 10^{-9} C , {\epsilon}_{0}=8.85 \times {10}^{-12} \text{ SI units}$

2) The triangle is equilateral. By vertical component of electric field I mean electric field perpendicular to the plane of charge.

3) The plate is non conducting.