Although you can enter the courses in 360° notation into your calculator sometimes it will automatically acquire a minus sign. This is because the right-angled triangle you are solving could be in any one of the four quadrants making up a compass. The answer

QUADRANTAL |
DEGREES |
QUADRANTAL |
DEGREES | ||

NOTATION |
NOTATION | ||||

NORTH |
360 |
NORTH |
000 | ||

N5 ° |
W |
355 |
N5 ° |
E |
005 |

N 10 ° |
W |
350 |
N 10 ° |
E |
010 |

N 15 ° |
W |
345 |
N 15 ° |
E |
015 |

N20 ° |
W |
340 |
N20 ° |
E |
020 |

N25 ° |
W |
335 |
N25 ° |
E |
025 |

N30 ° |
W |
330 |
N30 ° |
E |
030 |

N35 ° |
W |
325 |
N35 ° |
E |
035 |

N40 ° |
W |
320 |
N40 ° |
E |
040 |

N45 ° |
W |
315 |
N45 ° |
E |
045 |

N50 ° |
W |
310 |
N50 ° |
E |
050 |

N55 ° |
W |
305 |
N55 ° |
E |
055 |

N 60 ° |
W |
300 |
N60 ° |
E |
060 |

N65 ° |
W |
295 |
N65 ° |
E |
065 |

N 70 ° |
W |
290 |
N70 ° |
E |
070 |

N75 ° |
W |
285 |
N75 ° |
E |
075 |

N 80 ° |
W |
280 |
N80 ° |
E |
080 |

N86 ° |
W |
275 |
N86 ° |
E |
085 |

WEST |
270 |
EAST |
090 | ||

S85 ° |
W |
265 |
S85 ° |
E |
095 |

S80 ° |
W |
260 |
S80 ° |
E |
100 |

S75 ° |
W |
255 |
S75 ° |
E |
105 |

S70 ° |
W |
250 |
S70 ° |
E |
110 |

18.4 Quadrantal Notation (continued overleaf)

18.4 Quadrantal Notation (continued overleaf)

QUADRANTAL DEGREES QUADRANTAL DEGREES

S60 ° |
W |
240 |
S60 ° |
E |
120 |

S55 ° |
W |
235 |
S55 ° |
E |
125 |

S50 ° |
W |
230 |
S50 ° |
E |
130 |

S45 ° |
W |
225 |
S45 ° |
E |
135 |

S40 ° |
W |
220 |
S40 ° |
E |
140 |

S35 ° |
W |
215 |
S35 ° |
E |
145 |

S30 ° |
W |
210 |
S30 ° |
E |
150 |

S25 ° |
W |
205 |
S25 ° |
E |
155 |

S20 ° |
W |
200 |
S20 ° |
E |
160 |

S 15 ° |
W |
195 |
S 15 ° |
E |
165 |

S 10 ° |
W |
190 |
S 10 ° |
E |
170 |

S5 ° |
W |
185 |
S5 ° |
E |
175 |

SOUTH |
180 |
SOUTH |
030° could be = 30° east from north = = 30° east from south = = 30° west from north = 30° west from south A course of 030° could be = 30° east from north = = 30° east from south = = 30° west from north = 30° west from south 18.4 (Continued) is the same for each quadrant. Traditionally, courses used to solve the traverse are described as between 0-90° east or west from north or south. You must work out which quadrant your answer is in and turn it into 360° notation. There is no snappy formula to provide the answer. You must work it out (see the tables in Figure 18.4). Chartmaking Home-Made Charts Charts for Coastal Passages Representing our three-dimensional world on two-dimensional paper warps reality. The distortion used on a particular map is called its projection. In 1569 Gerard Kramer, known professionally as Gerardus Mercator, invented the projection that bears his name. Mercator's projection was an instant hit with navigators because it allowed them to draw their courses as straight lines. The secret behind this is that a Mercator chart thinks the world is a cylinder, and lines of longitude, instead of meeting at the poles, are parallel to each other. They do this by growing further and further apart as you travel north or south from the equator (see Mercator charts in Figure 19.1). This is only possible because the latitude scale varies while the longitude scale is constant. Every single second of latitude is slightly larger than its predecessor, whereas in real life, or on a globe, they are equal. Mercator never explained how he drew his charts. It was 30 years after his first chart that an Oxford don called Edward Wright worked out the maths behind the Mercator projection. |

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