Level 1: Core Concepts Check (Aiming for a Pass - 'S')

1. Define: What does it mean for two triangles to be "congruent"?

2. List: Name the four cases (conditions) used to prove triangle congruence.

3. Identify: In a right-angled triangle, what do the letters 'H' and 'S' stand for in the RHS case?

4. Recall: If △ABC≡△PQR, which angle corresponds to AB^C?

5. Identify: To use the SAS case, where must the equal angle be located relative to the equal sides?

Level 2: Connecting the Dots (Aiming for a Credit - 'C'/'B')

1. Explain: A student tries to prove two triangles are congruent using "Angle-Side-Side" (ASS). Explain why this is not a valid case for congruence.

2. Apply (Proof): In quadrilateral ABCD, the diagonals AC and BD bisect each other at point O. Prove that △AOD≡△COB.

3. Describe: Based on your proof in Q2, what can you conclude about the sides AD and BC? Give a reason.

Level 3: Exam Challenge (Aiming for a Distinction - 'A')

Proof Analysis: In an isosceles triangle PQR, where PQ = PR, the perpendiculars from vertices Q and R to the opposite sides (PR and PQ) meet the sides at Y and X respectively.

(a) Draw a clear diagram of this situation. (b) Prove that △PQY≡△PRX. (c) Hence, prove that QY = RX.