Chapter 15.2 (Mathematics 5)

Perpendicular and parallel lines

Identifying and drawing perpendicular lines

Group Activity 5

In groups of four:

  1. Take a piece of paper.
  2.  Fold a paper once to form a straight edge.
  3. Fold the paper again such that the straight edge overlaps as shown.
  1. Open the paper and draw the fold lines using a pencil.
  2. Discuss the results and share with other groups.

Note

  1. Lines AB and CD meet at right angle.
  2. AB and CD are perpendicular lines.

Perpendicular lines in the classroom and the environment

Which lines are perpendicular?

Drawing perpendicular lines

Group Activity 6

In pairs:

  1. Draw a horizontal line on a paper.
  2. Mark a point A on the line.
  3. Place a right corner at A.
  4. Draw a vertical line using the vertical edge of the right corner.
  5. Discuss and share the results with other groups.
    ​Note the two lines drawn are perpendicular.
  6. Draw other perpendicular lines using a ruler, a book and other objects with right corners.

Exercise C

  • AB and BC
  • AB and DC
  • AB and AD
  • BC and CD
  • BC and AD
  • CD and DA
  • EF and FG
  • FG and GE
  • GE and EF
  1. line  and line 
  2. line  and line 
  3. line  and line 

C4

In pairs, draw perpendicular lines using:

  1. A ruler.
  2. Edges of a book.
  3. Edges of a duster.
  4. Edges of a box.
  5. Edges of a piece of timber.

C5

Identify perpendicular lines at home.

Identifying and drawing parallel lines

Group Activity 7

In pairs:

  1. Put a ruler on a piece of paper.
  2. Without moving the ruler, draw two lines using the two opposite edges of the ruler.
  3. Discuss the results and share with other groups.

Note

  1. The two lines drawn can never meet.
  2. The distance between the two lines is the same.
  3. The two lines are parallel.

Parallel lines in the classrooms and the environment

Which lines are parallel?

Drawing parallel lines

Group Activity 8

In pairs:

  1. Draw a horizontal line.
  2. Mark a point A on the line.
  3. Place a right corner at A.
  4. Mark a point B above A.
  5. Move the right corner to B.
  6. Draw a line using the horizontal edge of the right corner.
  7. Discuss and share the results with other groups.

Note

  1. The two lines drawn are parallel.
  2. Draw other parallel lines using objects with right corners.

Exercise D

D2

Name three pairs of parallel lines in the figure shown:

D3

Identify parallel lines at home.

D4

In pairs, draw parallel lines using:

  1. A ruler.
  2. Edges of a book.
  3. Edges of a duster.
  4. Edges of a box.
  5. Right corner.