## Elementary Geometry for College Students (6th Edition)

The length of the base must be between $0$ and $20~cm$
If the legs are close together and the vertex angle is close to $0^{\circ}$, the length of the base will be close to zero. If the legs are far apart and the vertex angle is close to $180^{\circ}$, the length of the base will be close to the sum of the two legs, that is $20~cm$. The length of the base must be between $0$ and $20~cm$