# Equivalent Resistance

1. Mar 1, 2008

### rootX

1. The problem statement, all variables and given/known data
Find equivalent resistance in:
http://img135.imageshack.us/img135/585/62083770ay3.jpg

2. Relevant equations

3. The attempt at a solution
my
r_eq^-1 = (30+60)^-1+(40+10)^-1
this is wrong.
do i need to include 8 and 4 ohm resistors

2. Mar 1, 2008

### stewartcs

$$R_{eq} = \frac{R_1 \cdot R_2}{R_1 + R_2}$$