Question

1. sas a) additional known statement:

reason:

b) information still needed:

to prove the \\( \delta \cong \\) by \\( \underline{\text{sas}} \\)

Explanation:

Step1: Identify vertical angles

Vertical angles are equal. So, \(\angle DBR=\angle TRS\) (vertical angles are congruent).

Step2: Recall SAS (Side - Angle - Side) criterion

For SAS, we need two sides and the included angle. We already have one pair of sides equal (marked in the figure) and the vertical angles (the included angles).

Answer:

a) Additional Known Statement: \(\angle DBR=\angle TRS\). Reason: Vertical angles are congruent.
b) Information still needed: Another pair of sides (either \(DB = RT\) and \(BR=RS\) or \(DR = BT\) and \(BR = RS\))