# Angles

## Measuring Angles with a Protractor

- Before measuring, estimate how many degrees the angle is.
- Place the
**cross-hairs** of the **protractor** at the vertex of the angle (the point where the two lines meet).
- Place the base line of the protractor on one of the lines making the angle.
- Follow the second line and choose which of the outer rings has the correct number of degrees.
- To measure angles greater than 180 degrees, it is easier to measure the smaller angle and subtract from 360.

## Types of Angles

DIAGRAM | NAME OF ANGLE | SIZE OF ANGLE |

| Acute angle | Less than 90° |

| Right angle | Equal to 90° |

| Obtuse angle | Between 90° and 180° |

| Straight angle | Equal to 180° |

| Reflex angle | Between 180° and 360° |

## Compass Bearing

**Cardinal Points** - Directions in *words* e.g. north, south, east, west, north-east, south-east

**Compass Bearings** - Directions in numbers of *degrees* that are measured *clockwise from north* as follows:

- North - 0°
- North-east - 45°
- East - 90°
- South-east - 135°
- South - 180°
- South-west - 225°
- West - 270°
- North-west - 315°

## Question - Orienteering

Orienteering is a sport that uses navigational skills of reading maps and compasses while running through mountains and valleys. If I leave home and
I travel the following legs of my journey, how far and at what bearing from home will I be?
*(In your sketch, use a scale of 1 cm for each 1 km.)*

- 2 km at 0°
- 3 km at 90°
- 4 km at 180°
- 3.6 km at 236°

**Answer**

I'm home

## Did You Know That...?

**Mandalas** are complex geometric designs for quiet contemplation in the Buddhist and Hindu religions.