# Introduction

This week we focus on the Solids in Contact topic. This topic is all about drawing Orthographic Views of tangential solids. The shapes that we need to focus on are Cones, Spheres, Hemispheres, Pyramids and Cylinders. It is important to know the difference between Solids in Contact and Interpenetration of Solids:

- Solids in Contact - Solids touch each other but do not intersect
- Interpenetration of Solids - Solids cut into one another.

It is even more important that you realise that although they are different topics they share the same fundamentals.

# Syllabus Learning Outcomes

The image below shows the Orthographic Projection portion of the DCG Syllabus. The parts related to Solids in Contact are highlighted.

# What You Need to Know!

### Ordinary Level

- Find a given point on a Cylinder, Cone (generator and horizontal section methods), Sphere and Pyramid in all Orthographic Views.
- Draw a combination of 2 of a Cone, Sphere, Cylinder, Hemisphere and Pyramid in mutual contact (including Points of Contact).
- Draw a combination of 3 of a Cone, Sphere, Cylinder, Hemisphere and Pyramid in mutual contact (including Points of Contact).

### Higher Level

- Draw a combination of 2 and 3 of a Cone, Sphere, Cylinder, Hemisphere and Pyramid in mutual contact using
(including Points of Contact)*Loci* - Find the traces of Tangent Planes to a Sphere and a Cone individually
- Find the trace of a Tangent Plane to both a Sphere and Cone

# Practice Questions

## Practice Textbook Questions

(Anderson, 2014)

- P49 Q8
- P49 Q9
- P52 Problem 3
- P53 Problem 4
- P57 Q2
- P57 Q3

## Past Exam Papers

- 2009 A-4
- 2011 A-4
- 2013 A-2
- 2017 A-3

I hope your revision is going well and that this week you'll enjoy looking back at some Solids in Contact. Again if you have any questions or opinions please comment below.

### References

Leaving Certificate Design and Communication Graphics Syllabus. (2006). Dublin: The Stationary Office.

Anderson, D. (2014). *Graphics in Design and Communication: One Volume Edition*. Dublin: Gill & Macmillan.