MathDB

Let

R

be the rectangle in the Cartesian plane with vertices at

(0,0), (2,0), (2,1),

and

(0,1)

R

can be divided into two unit squares, as shown; the resulting figure has seven edges. [asy] size(3cm); draw((0,0)--(2,0)--(2,1)--(0,1)--cycle); draw((1,0)--(1,1)); [/asy] Compute the number of ways to choose one or more of the seven edges such that the resulting figure is traceable without lifting a pencil. (Rotations and reflections are considered distinct.)

12

Problems(1)