DCG Revision - Basic Constructions

Basic Constructions are the foundation upon which many topics are built, in particular Solids in Contact. They can come up as a short question in their own right or they also can also come up as part of a long question.

Loci is most commonly used in Solids in Contact questions but can come up as a stand alone question in Section A too.
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Best of luck with your revision!
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SYLLABUS LEARNING OUTCOMES(Leaving Certificate Design and Communication Graphics Syllabus, 2006)

Key Constructions You Need to Know

• Bisect a line
• Bisect an angle
• Construct perpendiculars to lines
• Dividing a line into a given number of parts or a given ratio
• Construct a circumscribing and inscribing circle around and inside a triangle
• Find the centre of a circle given 4 points or 2 chords
• Construct a triangle given its base, top angle and altitude
• Construct a triangle given the top angle, length of 1 side and the base
• Construct a triangle given the perimeter and the ratio of its sides
• Construct a tangent to a circle from a point on the circle and a point outside the circle
• Construct an external and internal tangent between 2 unequal circles
• Construct external and internal tangent arcs to 2 circles

THE KEY USES OF LOCI YOU NEED TO KNOW

• Construct a circle to touch a line and 2 given points
• Construct a circle to touch both arms of an angle and a given point
• Construct a circle to touch a given circle and 2 given points
• Construct a circle to touch 3 given circles
• Construct a circle to touch a line and 2 given circles

Practice Textbook Questions (Anderson, 2007)

1. P9 Q8
2. P10 Q11
3. P10 Q12
4. P16 Q8
5. P16 Q9
6. P17 Q11
7. P23 Q3
8. P26 Q16
9. P26 Q19

Past Exam Paper Questions

1. 2012 A-3
2. 2016 A-4
3. 2017 A-3

References

Leaving Certificate Design and Communication Graphics Syllabus. (2006). Dublin: The Stationary Office, p.15.
Anderson, D. (2007). Graphics in Design and Communication 1. Dublin: Gill & Macmillan, pp.9-26.