Question

To prove that ΔAED ˜ ΔACB by SAS, Jose shows that StartFraction A E Over A C EndFraction = StartFraction A D Over A B EndFraction.

Triangle A E D is shown. Line segment B C is drawn from side A D to A E to form triangle A C B.

Jose also has to state that

Answer 1

He must state that the included angles are equal: ∠EAD = ∠CAB (equivalently ∠DAE = ∠BAC).
Justification: C lies on ray AE and B lies on ray AD, so the angle between AC and AB equals the angle between AE and AD.