Regular Polygons and Bearings
Primary 6 · Mathematics
Regular Polygons and Bearings
Lesson 4 of 5
16 min
Let's begin
Gatete is a guide in Volcanoes National Park. Before sunrise he leads visitors up the slopes of Bisoke. There are no road signs in the forest, so he gives directions like this: "Walk on a bearing of 045°."
What does that number mean, and why does it start with a zero? By the end of this lesson you will be able to read and give directions like a guide.
The four main directions are North (N), East (E), South (S) and West (W). In Kinyarwanda they are Amajyaruguru, Iburasirazuba, Amajyepfo and Iburengerazuba. The sun rises in the east and sets in the west.
Halfway between them are four more: North-East (NE), South-East (SE), South-West (SW) and North-West (NW). On this eight-point compass, neighbouring points are 45° apart, because 360° ÷ 8 = 45°.
A bearing is a direction given as an angle. It always follows three rules:
Three figures prevent mistakes: a visitor who hears "zero four five" knows that no digit was missed.
The blue arrow shows the clockwise direction. Here are the bearings of the eight compass points:
| Direction | N | NE | E | SE | S | SW | W | NW |
|---|---|---|---|---|---|---|---|---|
| Bearing | 000° | 045° | 090° | 135° | 180° | 225° | 270° | 315° |
A full turn is 360°, which brings you back to North, so 360° points the same way as 000°. We normally write North as 000°.
Worked example 1
where is the bearing 215°? It is more than 180° and less than 270°, so it lies between South and West.
Worked example 2
Gatete faces East and turns clockwise through 180°. East is 090°, and 090° + 180° = 270°, so he now faces West.
Worked example 3
you measure the anticlockwise angle from North to a line and get 50°. The bearing is 360° − 50° = 310°, which lies between West and North.
Tip
North, clockwise, three figures. Say it like a chant before every bearing question.
And think of a clock face: North is at 12, East at 3, South at 6 and West at 9.
Answers
What you learned today
Sources and credits
Written by Ganzaa: the teaching on compass points and three-figure bearings, the compass-rose drawing and all the worked examples. No openly licensed lesson on three-figure bearings was found, so this part is Ganzaa's own. Only the steps for placing a protractor were adapted from Siyavula.
Quick check
What is the three-figure bearing of South-West?
