You will discover the notions of perpendicular and parallel straight lines and segments and the ways of drawing them.
Learning effect
You recognise the position of perpendicular, parallel straight lines and segments.
You draw perpendicular, parallel straight lines and segments.
You describe the position of the straight lines and the segments in English.
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Today you are going to revise the material related to the mutual position of the lines and the segments in the plane.
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Part 1. On the basis of the material you have studied on your own answer the following questions:
How many common points can the lines situated in the same plane have?
How do we call the lines which have no common points?
Are the lines which intersect at one pointpoint point always perpendicular?
What symbol is used to describe the perpendicularity and the parallelism?
Task 1
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Draw the m line in your notebook. Then, using the set squareset squareset square and the rulerrulerruler draw:
the k line perpendicular to the m line,
the t line parallel to the m line.
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On the basis of the material you have learned answer the following questions:
How can we check, if two segments are perpendicular?
Do perpendicular segments have to have one common pointpoint point?
How can we check if two segments are parallel?
Are the segments which have no the common points always parallel?
Task 2
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Open the applet. Move the A, B, C, D vertices so that the segments AB and CD are perpendicular (stage 1) or parallel (stage 2).
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Part 2. Summarise the material you have learned by answering the following questions:
What is the possible mutual position of two straight lines situated in the plane?
What property do the parallel segmentsparallel segments parallel segments have?
Are the segments situated at one straight linestraight linestraight line parallel?
Task 3
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An extra task:
Draw a straight linestraight linestraight line a. Make a construction of an m line parallel to the line using the compass. Find out the instructions on the Internet.
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Remember:
The straight lines which intersect at the right angleright angle right angle are called perpendicular lines and are marked with the symbol ⊥. The segments which are situated within the perpendicular lines are called perpendicular segments.
The straight lines which do not have common points (or cover one another) are called parallel linesparallel linesparallel lines and they are marked with the symbol ∥. Segments which are situated within the parallel linesparallel linesparallel lines are called parallel segmentsparallel segments parallel segments.
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Do the summary tasks.
Exercises
Exercise 1
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Exercise 2
Draw the following segments in your notebook AB, CD, EF, DF so that segments AB and CD are perpendicular, segments CD and EF are parallel, segments EF and DF are perpendicular.
Describe the position of the segments in English:
AB and DF
CD and DF
EF and AB
AB ∥ DF
CD ⊥ DF
EF ⊥ AB
Exercise 3
Describe the mutual position of the straight lines presented in the drawing below In English.
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Straight lines t and g are parallel.
Straight lines c and t, c and g and d and b are perpendicular.