what is the electric field at the centre of an equilateral triangle if three point charges are placed at the three corners of it?

No electric field at the centre, bcause the resultant electric field of any two charges will nulify the electric field for the another. As the triangle is equilateral so distance from any corner to centre will be same, so field for any corner charge will be equal.

SO NET ELECTRIC FIELD AT THE CENTRE IS 0 (ZERO)