Parallel, intersecting, and perpendicular lines

1. Unit 3
Parallel, Intersecting and Perpendicular lines

2. Parallel, Intersecting and
Perpendicular lines
• Line CD is parallel to line AB.
A B
C D
• Lines that never cross are called parallel lines.

3. Parallel, Intersecting and
Perpendicular lines
• Line EF intersects line AB at point K.
F
A B
K
E
• Intersecting lines are two or more lines that meet
at a common point.

4. Parallel, Intersecting and
Perpendicular lines
• Line GH is perpendicular to line AB.
G
A B
E
• Perpendicular lines are lines that intersect each
other at right angles.

5. Lets see if you can tell the difference
between parallel, intersecting and
perpendicular….
Parallel

6. Lets see if you can tell the difference
between parallel, intersecting and
perpendicular….
intersecting

7. Lets see if you can tell the difference
between parallel, intersecting and
perpendicular….
Perpendicular

8. How about this one
Parallel, Intersecting and
Perpendicular

9. So how do we draw perpendicular
lines?
• Method 1
• Place a set square on line AB with the right angletouching the
line.
A B

10. So how do we draw perpendicular
lines?
• Then drawalong the side of the set square that is at right
angles to line AB.
A B

11. Drawing perpendicular lines
• Use your set square to draw lines that are
perpendicular to the following lines:
• 1.

12. Drawing perpendicular lines
• Use your set square to draw lines that are
perpendicular to the following lines:
• 2.

13. Drawing perpendicular lines
• Use your set square to draw lines that are
perpendicular to the following lines:
• 3.

14. Drawing perpendicular lines
• Use your set square to draw lines that are
perpendicular to the following lines:
• 4.

15. What if you don’t have a set square?
• Method 2: Draw a dot (X) on the middle of
line AB.
• Place the center of the protractor on the dot
A B
X

16. What if you don’t have a set square?
• Now draw another dot (Y) at the 90° mark on
the protractor.
Y
A B
X

17. What if you don’t have a set square?
• Draw a line to connect X and Y. Line XY is
Perpendicular to line AB.
Y
A B
X

18. Let’s try it!
• Let’s draw some perpendicular lines on page
20!
#1
A
B
X
Y

19. • The Compass
3rd method for drawing
perpendicular lines

20. Start with a line segment AB

21. Place the compass on one end of the
line segment.

22. Set the compass width to
approximately two thirds of the line
length. The actual width does not
matter.

23. Without changing the compass width,
draw an arc above and below the line

24. Again without changing the compass
width, place the compass point on the
other end of the line.

25. Draw an arc above and below the line
so that the arcs cross the first two.

26. Using a ruler, draw a line between the
points where the arcs intersect.

27. This line is perpendicular to the first
line and bisects it (cuts it at the exact
midpoint of the line.

28. Lets practice on page 22!
• Draw a line on the paper provided and use
your compass!

29. Lets review and see what you know!
• http://www.mangahigh.com/en/maths_game
s/shape/understanding_properties_of_shape/
recognise_perpendicular_and_parallel_lines