Trigonometry

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Trigonometry

I must go down to the seas again, to the lonely sea and the sky,  

And all I ask is a tall ship and a star to steer her by.

John Masefield

Trigonometry background

Angles of elevation and depression

The angle of elevation is the angle between the horizontal and a direction above

the horizontal (see figure 7.1). The angle of depression is the angle between the

horizontal and a direction below the horizontal (see figure 7.2).

Bearing

The bearing (or compass bearing) is the direction measured as an angle from

north, clockwise (see figure 7.3).

angle of elevation

Figure 7.1

angle of depression

Figure 7.2

150°

E

this direction is

a bearing of 150°

W

N

S

Figure 7.3

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