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The bearing of Y from X is 275°, find the bearing of X from Y

Step by step, with the reason for every step · Three-figure bearings and back bearings · Geometry

Step by step

The question

Question: the bearing of Y from X is 275°: find the bearing of X from Y.

1 Draw the north line

A bearing starts at the north line.

It is measured clockwise, the way a clock turns, and written with 3 figures.

At Y we draw a north line too.

The two north lines are parallel.

2 Turn round

From Y back to X is the opposite direction: half a turn more, 180°.

275 is more than 180, so we take 180 away: 095°.

Adding would go past 360°.

back bearing = 275° − 180° = 095°

Why 180?

The north lines are parallel.

The angles between the path and the two north lines add up to 180°, as in the parallel lines lesson.

the north lines are parallel:
co-interior angles add to 180°

Careful!

A bearing is under 360°.

Over 180°, we take 180 away.

Careful: not 275 + 180 = 455° ✗

3 Check

Let's check: the two bearings differ by exactly 180°, half a turn.

So it is right!

275° and 095° differ by 180°

Let's look back.

First: draw the north line.

Then: turn round.

Last: check.

Answer
Careful: not 275 + 180 = 455° ✗

Your turn

Try this one yourself, then check:

Find the bearing of X from Y.
Show the answer
bearing 065°

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