a) Between C and D :
The resistors R2, R3 and R4 are in series. They can be replaced by an equivalent resistance Rs where
Rs = R2 + R3 + R4 = 3 + 3 + 3 = 9 Ω
The resistance R5 and Rs are in parallel between the points C and D.
The equivalent resistance between C and D then
Thus the equivalent resistance between C and D is 2.25 Ω.
b) Between A and B :
Now the resistors R1 , Rp and R6 are in series between the points a and B.
The equivalent resistance between A and B is
RAB = R1 + Rp + R6 = 3 +2.25 + 3 = 8.25 Ω.
