Textbook of Engineering Drawing, Second Edition
- ____ Geometrical Contructions 4.9
Fig. 4.14
- Where this arc cuts the vertical centre line number the point 6.
- This is the centre of a circle inside which a hexagon of side AB can now be drawn.
- Bisect the distance 4-6 on the vertical centre line.
- Mark this bisection 5. This is the centre in which a regular pentagon of side AB can now
be drawn.
- On the vertical centre line step off from point 6 a distance equal in length to the distance
5-6. This is the centre of a circle in which a regular heptagon of side AB can now be
drawn.
- If further distances 5-6 are now stepped off along the vertical centre line and are numbered
consecutively, each will be the centre of a circle in which a regular polygon can be
inscribed with sice of length AB and with a number of sides denoted by the number
against the centre.
- To inscribe a square in a triangle.
construction (Fig. 4.15)
- Draw the given triangle ABC.
- From C drop a perpendicular to cut the base AB at D.
- From C draw CE parallel toAB and equal in length to CD.
- Draw AE and where it cuts the line CB mark F.
- From F draw FG parallel to AB.
- From F draw F J parallel to CD.
- From G draw GH parallel to CD.
- Join H to 1.
Then HJFG is the required square.
