Find the equivalent resistance of the triangular bipyramid between the points.

a. `A` and `C` , b. D` and `E`

Answer

A, B, C

Explanation

a. points `D` and `E` are symmetrically located with respect to points `A` and `C`. The circuit can be redrawn as shown in figure.

This is combination of a balanced Wheatstone bridge in parallel with a resistance `R`. so the resistance between `B` and `D` (or `E`) can be removed.
`1/R_(AC)=1/R+1/(R/2+R/2)+1/(2R)`
or `R_(AC)=(2R)/5`
b. With respect to `D` and `E`, points `A, B`, and `C` all are symmertrically located. Hence, the simplified circuit can be drawn as shown in figure.

`:. R_(DE)=R/3+R/3=(2R)/3`