There is an interesting puzzle from Jiří Matoušek's book Invitation to Discrete Mathematics, problem 1.2.8, which confused me lots of time.
Divide the following figure into $7$ parts, all of them congruent (they only differ by translation, rotation, and possibly by a mirror reflection). All the bounding segments in the figure have length $1$, and the angles are $90$, $120$, and $150$ degrees.
Did I miss anything from the question ?