O-LevelMathematicsGeometry4024/11 · Oct/Nov 2022 · Q193 Marks

19 ABD is an equilateral triangle. C lies on DB and AC is perpendicular to DB. Show that triangle ADC is congruent to triangle ABC. Give a reason for each statement you make. [Figure showing triangle ABD with C on DB and AC perpendicular to DB]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2022). The mark or mark type is shown in brackets.

[3] AC = AC common [side]
AD = AB equilateral [triangle]
∠ACD = ∠ACB = 90°
[Congruent] RHS
B2 for two pairs of equal sides/angles with correct reasons
or B1 for one pair of equal sides/angles with correct reason or for two appropriate pairs with no or incorrect reasons

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.

Topic: Geometry, O-Level Mathematics (syllabus 4024). Structured question, 3 marks.
Source: O-Level Mathematics, Oct/Nov 2022 Paper 1 Variant 1, question 19.

Questions and mark schemes are from past examination papers and remain the copyright of the exam board. How Oracle Prep builds its content