  A previously overlooked constraint for the distribution of entanglement in
three-qubit systems is exploited for the first time and used to reveal a new
genuine tripartite entanglement measure. It is interpreted as the area of a
so-called concurrence triangle and is compared with other existing measures.
The new measure is found superior to previous attempts for different reasons. A
specific example is illustrated to show that two tripartite entanglement
measures can be inequivalent due to the high dimensionality of the Hilbert
space.
