Page 322 - Math Smart - 7

Use your protractor to measure
an angle of 108°. Draw
construction mark at 108°.

Use your construction mark. Place the centre of your protractor
The size of the internal
4 on the second construction mark
angle of a regular Measure and draw a 40-mm
pentagon will always be line that passes through the Measure an angle of 108° and make
108° regardless of the first construction mark. Make a a third construction mark at 108°.
length of the sides. second construction mark.

40 mm

Repeat Steps 3 and 4 until you
have completed the 5
angles and 5 sides of
the pentagon.

Check My
Understanding

O Use a protractor to construct
a) an equilateral triangle with sides 42 mm and internal angles of 60°.
b) a regular hexagon with sides 5 cm and internal angles of 120°.
c) a regular octagon with sides 55 mm and Internal angles of 135°.
d) a regular pentagon with sides 62 mm and internal angles of 108°.
0 Construct a parallelogram ABCD such that AB = 8.5 cm, BC = 6.5 cm and AABC = 65'
Q Construct a rhombus WXYZ with diagonals WY = 9 cm and XZ=1 cm.

Q Draw a regular polygon with side lengths of 48 mm and internal angles of 120°.
What type of regular polygon have you drawn?
A Draw a regular hexagon with side lengths of 58 mm.

UNIT 14 Geometrical Constructions