P1.2.2 - Parallel and perpendicular lines

Conditions for two straight lines to be parallel or perpendicular to each other.

Use parallel and perpendicular lines to connect the rule to the data and decision in the question.

This matters because parallel and perpendicular lines determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply parallel and perpendicular lines to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: Parallel and perpendicular lines is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.