Bearings
There are four main directions on a compass; north, south, east and west.
A compass can be used to describe a direction. Another method of describing directions is using bearings.
Ships use bearings to navigate. A bearing is measured in degrees.
Example
This plane is flying at an angle of 48° from North. The bearing it flies at is 048°.
This plane is flying at an angle of 20° anticlockwise from North. Since a bearing is measured clockwise, the bearing it flies at is 360 - 20 = 340°.
Question
Measure the bearing of the shark from the ship.
Method 1
Draw a line between the ship and the shark. Draw a line pointing North from the ship.
The shark is more than 180° clockwise from North. Place the centre of the protractor on the ship and 180° facing North.
Measure the angle clockwise from 0° to the line between the ship and the shark. In this case the measurement is 100°.
A bearing is measured from North. Add the angle to 180°:
\(180 + 100 = 280\)
The bearing of the shark from the ship is 280°.
Method 2
Draw a line between the ship and the shark. Draw a line pointing north from the ship.
The shark is more than 180° from North. Place the centre of a protractor on the ship and 0° facing North.
Measure the angle anticlockwise from 0° to the line between the ship and the shark. In this case the measurement is 80°.
A bearing is measured clockwise from North. Subtract this angle from 360°.
\(360 - 80 = 280\)
The bearing of the shark from the ship is 280°.