∑ DANEMATHICS
FREE CAPS MATHS RESOURCES
Grade 8–9 · Geometry of 2D Shapes
Construction of Geometric Figures
MEMORANDUM
Name:
Class:
Date:
Mark
/ 13
Answer all questions. Show all your working — marks are awarded for method as well as the final answer. Teacher copy: accept any correct equivalent method.
- 1What two instruments may you use in a construction?(1)A compass and a ruler (straight edge) only.✓ (1)
- 2Why must you not rub out your arcs?(1)The arcs are the working — the marks are awarded for them.✓ (1)
- 3When bisecting AB, how wide must the compass be opened?(2)More than half of AB, or the arcs will not cross.✓✓ (2)
- 4What angle does a perpendicular bisector make with the line?(1)90°✓ (1)
- 5How do you construct a 30° angle?(2)Construct 60°, then bisect it.✓✓ (2)
- 6How do you construct a 45° angle?(2)Construct 90°, then bisect it.✓✓ (2)
- 7Which side is usually the most convenient to draw first in an SSS construction?(1)Usually the longest side, because it gives a clear base — but any of the given sides can be used.✓ (1)
- 8Can a triangle with sides 3 cm, 4 cm and 9 cm be constructed?(2)No — 3 + 4 = 7, which is less than 9, so the arcs never meet.✓✓ (2)
- 9Each angle of a constructed equilateral triangle measures…(1)60°✓ (1)
TOTAL: 13 marks