Einthoven's triangle, what is the value of lead III when lead I = 2 mv and Lead II =1 mv: (A) 1, (B) 2, (C) 3, (D) 4
Answer is A. According to Einthoven's triangle,  voltage in I + III = voltage in II
So Voltage in III = II-I
= 1-2 = -1
The value is 1.