Equivalent resistance 5

each triangular part has 3 3ohm resistance out of which 2 are in series and one is in parallel so Req for each triangle=2ohm now there are 3 triangles in series which are parallel to one triangle so R1=3x2ohm = 6ohm Rtotal=6x2/(6+2)=3/2=1.5ohm

Every triangular circuit of $3\times 3\Omega$ resistors connected at two apexes is actually a parallel circuit of $3\Omega + 3\Omega$ and $3\Omega$ or $6\Omega // 3\Omega = 2\Omega$ .

Therefore, the equivalent resistance $R_{eq} = (2\Omega + 2\Omega + 2\Omega) // 2\Omega = 6\Omega // 2\Omega = \frac{6\times 2}{6+2}\Omega=\boxed{1.5\Omega}$

The given circuit can be rearranged as follows:

Alt text

The equivalent resistance will be $\boxed {1.5 ohms}$

Take any triangle, the base of each triangle(which is the side of a square) is parallel to the other two resistors on the other sides of the triangle. The resultant of each triangle is 2 ohms. The three sides of square are parallel to side ab. The net resistance is 1.5 ohms.