In figure, ∆PQR is an equilateral triangle with co-ordinates of vertices Q and R as (-2, 0) and (2, 0). Find the co-ordinates of the vertex P.

∵ ∆PQR is an equilateral triangle
∴ PQ = PR = QR
⇒ PQ = QR
⇒ PQ = 4
OQ = 2
In right triangle POQ,
OP2 + OQ2 = PQ2 |By Pythagoras Theorem
⇒ OP2 + (2)2 = (4)2