Page 127 - Mathematics Coursebook

12.4 Constructing squares, rectangles and polygons

) Exercise 12.4

1 Make an accurate drawing of a square with side length:
a 4 cm b 7.2 cm.
2 Make an accurate drawing of a rectangle with:
a length 5 cm and width 2 cm b length 10 cm and width 6 cm.
3 Make an accurate drawing of a regular hexagon with a side length of 4 cm
and an internal angle of 120°.

120°
4 cm

4 Make an accurate drawing of a regular octagon with a side length of 5 cm
and an internal angle of 135°.

135°
5 cm
5 The diagram shows a pentagon on top of a square on top of a rectangle.
The length of the rectangle is twice the length of the side of the square.
The width of the rectangle is equal to the length of the side of the square.
The pentagon has a side length of 4 cm and an internal angle of 108°.
Make an accurate copy of the diagram.

Summary

You should now know that: You should be able to:
+ Parallel lines are lines that never meet. + Use a ruler to measure and draw straight lines
+ Perpendicular lines are lines that meet at a right accurately, to the nearest millimetre.
angle (90°). + Use a ruler and set square to draw parallel and
+ There are two types of triangle construction that perpendicular lines.
you need to be able to do. + Use a ruler and protractor to construct a triangle,
+ The first is known as SAS, which stands for Side given two sides and the included angle or two
Angle Side. angles and the included side.
+ The second is known as ASA, which stands for + Use a ruler and protractor to construct squares
Angle Side Angle. and rectangles.
+ To draw a square or a rectangle you only need to + Use a ruler and protractor to construct regular
know the lengths of the sides (you already know polygons, given a side and the internal angle.
that all the angles in a square and a rectangle + Draw accurate mathematical diagrams and
are 90°). constructions.
+ To draw a regular polygon, you need to know the
lengths of the sides and the size of the internal
angles.

126 12 Constructions