Step-by-step explanation:
Well, the 2 leads situated on the right and left wrist (or shoulders), AVr and AVL respectively, and the lead situated on the left ankle (or left lower abdomen) AVf, make up a triangle, known as "Einthoven’s Triangle". Information gathered between these leads is known as "bipolar". It is represented on the ECG as 3 "bipolar" leads. So,
information between AVr and AVl is known as lead l.
Information between AVr and AVf is known as lead ll
Information between AVl and AVf is known as lead lll