## Elementary Geometry for College Students (7th Edition)

Assuming, that $\overline{AC}=\overline{AB}=\overline{BC}$ triangle ABC is an equilateral triangle. This means $\angle ABC = 60^{\circ}$. But $\angle ABC = 90^{\circ}$ because ABCD is a square. Therefore $\overline{AC} \ne \overline {AB}$.