Page 123 - Cambridge Checkpoint Mathematics Coursebook 7_Slide 02
P. 123
12.2 Drawing perpendicular and parallel lines
12.2 Drawing perpendicular and parallel lines
Perpendicular lines are lines that meet at a right angle (90°).
You show that lines are perpendicular by using a small square symbol in the
corner (). You have already seen this in Unit 5.
Parallel lines are lines that never meet.
Th e perpendicular distance between the lines is always the same.
You show that lines are parallel by using an arrow symbol (→) on each line.
You can use a ruler and set square to draw parallel and perpendicular lines.
A B
Worked example 12.2 5 6 7 8
3
4
2
1
cm
a Draw a line segment AB 7.5 cm long. Mark the point C on the line AB where C is 4.5 cm from A.
B
C
A
Draw a line from C that is perpendicular to the line AB.
b Draw parallel lines 5 cm long that are a distance of 2 cm apart.
2
6
8
5
cm
4
3
7
1
a
First draw AB, 7.5 cm long.
Mark the point C on the line AB, so that AC is 4.5 cm.
A B Use the set square to draw a perpendicular line up
A C B from C.
cm cm 1 1 2 2 3 4 3 5 4 6 5 7 8
b First draw one line segment 5 cm long.
Place the set square at the end of this line and use it
to measure 2 cm up from the fi rst line.
Use the set square to measure another point 2 cm up
from the fi rst line.
Join these two points and make sure that the parallel
line is also 5 cm long.
F Exercise 12.2
1 Draw parallel line segments that are:
a 7 cm long and 1.5 cm apart b 9.8 cm long and 3.2 cm apart
2 Draw PQ 10 cm long. Mark the point R on PQ so that R is 3 cm from P.
Mark the point S on the line PQ so that S is 4.5 cm from Q.
Draw two lines, one from R and one from S, that are both perpendicular to the line PQ.
3 Draw UV 8 cm long.
a Draw a 4 cm line perpendicular to UV from the midpoint of UV. Label the ends X and Y.
b Draw a line, 4 cm long, from the midpoint of XY and perpendicular to XY. Label the ends W and Z.
c Check by measuring with a ruler that WZ is parallel to UV.
12 Constructions 121
