## Elementary Geometry for College Students (5th Edition)

1) Show that $\angle ABC\cong\angle ABD$. 2) Use method SAS for the following pairs: - $\angle ABC\cong\angle ABD$. - $\overline{BC}\cong\overline{BD}$ - $\overline{AB}\cong\overline{AB}$ (by Identity)
We have that $\overline{AB}\bot\overline{BC}$ and $\overline{AB}\bot\overline{BD}$ So $\angle ABC$ and $\angle ABD$ are both right angles, which means $\angle ABC\cong\angle ABD$. Furthermore, it is given that - $\overline{BC}\cong\overline{BD}$ - $\overline{AB}\cong\overline{AB}$ (by Identity) Now we have 2 sides and the included angle of $\triangle ABC$ are congruent with 2 corresponding sides and the included angle of $\triangle ABD$. That means according to method SAS, $\triangle ABC\cong\triangle ABD$.