Step 1: Recall that a right angle is 90° (a square corner, like the corner of a piece of paper). Step 2: Check each object: - Whiteboard: rectangular, has 4 right angles at its corners ✓ - Clock face: circular, no corners ✗ - Pencil sharpener: may be triangular or irregular, not typically a right angle ✗ - Round table: circular, no corners ✗ Step 3: The whiteboard corner is a right angle.