Higher Mathematics · Free original practice · 3 marks
Perpendicular line
Work through one question, use a small hint if needed, then compare your reasoning. Suggested marks are for self-assessment; independent subject review is pending.
A(−2, 5) and B(4, −1) lie on a line. Find the equation of the perpendicular bisector of AB.
A small hint
Find the midpoint first.
Worked explanation and suggested marking
The midpoint is (1, 2).
Up to 1 mark
AB has gradient −1, so the perpendicular gradient is 1.
Up to 1 mark
y − 2 = x − 1, hence y = x + 1.
Up to 1 mark
y = x + 1
What to watch for
- Use the midpoint, not either endpoint.