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掳 from North. The bearing it flies at is 048掳.
This plane is flying at an angle of 20掳 anticlockwise from North. Since a bearing is measured clockwise, the bearing it flies at is 360 - 20 = 340掳.
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掳 clockwise from North. Place the centre of the protractor on the ship and 180掳 facing North.
Measure the angle clockwise from 0掳 to the line between the ship and the shark. In this case the measurement is 100掳.
A bearing is measured from North. Add the angle to 180掳:
\(180 + 100 = 280\)
The bearing of the shark from the ship is 280掳.
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掳 from North. Place the centre of a protractor on the ship and 0掳 facing North.
Measure the angle anticlockwise from 0掳 to the line between the ship and the shark. In this case the measurement is 80掳.
A bearing is measured clockwise from North. Subtract this angle from 360掳.
\(360 - 80 = 280\)
The bearing of the shark from the ship is 280掳.