1718 WB1Z CH11 Lesson 1

• Wiskunde
• Middelbare school
• vwo
• Leerjaar 1

Recap CH5

- Parallel and perpendicular lines
-  Right, acute and obtuse angles
- Measuring and drawing angles and distances

Parallel lines

Lines a and b are parallel to each other.
Lines c, d and e are parallel to each other.

Notation:

Perpendicular lines

Lines s and t are perpendicular to each other.

Notation:

Angles & Degrees

A right angle is 90°
An acute angle is between 0° and 90°
An obtuse angle is between 90° and 180°



right angle                       acute angle                                  obtuse angle
90°                                       between 0° and 90°                  between 90° and 180°

Symmetry

There are two types of symmetry:
- Reflection symmetry
- Rotation symmetry
Figures can have no symmetry, one type of symmetry or two types of symmetry.

Reflection symmetry

If a figure could be folded in half, so both halves fit exactly on top of each other, we say a figure has reflection symmetry.
The line on which you would fold the figure is called the axis of symmetry.

Rotation symmetry

If a figure can be rotated less half a turn or less and fit exactly on themselves again, we say a figure has rotation symmetry.
If a figure fits onto itself after a quarter, a half and three quarters of a turn, we say it has rotation symmetry through 90°, 180° and 270°.




120° and 240°                                                      60°, 120°, 180°, 240° and 300°

Rotation symmetry

This figure has 7 identical parts, so 1/7th of
a turn will make it fit onto itself again.


The figure has rotation symmetry through

​7​​360°​​=51​7​​3​​°

51​7​​3​​°,102​7​​6​​°,154​7​​2​​°,205​7​​5​​°,257​7​​1​​°,308​7​​4​​°

Homework Tuesday

Chapter 11, make and correct:
R3, R5, R6, 2, 3, 4, 5, 6, 7, 8

bring your workbook