Define map declination and explain why it must be accounted for in navigation.

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Multiple Choice

Define map declination and explain why it must be accounted for in navigation.

Declination is the angular difference between magnetic north and true north. In navigation, maps are oriented to true north, while a compass points toward magnetic north. To make bearings from your compass usable on the map, you must adjust for this difference. If the declination is east, magnetic north is east of true north, so you add the declination to the magnetic bearing to get the true bearing. If it’s west, you subtract it. This correction is essential to keep your path aligned with the map and the real geography; without it, you’d drift off course by the size of the declination. Declination values change slowly over time as the Earth's magnetic field shifts, so updating the current local value is important. The other options describe distance between grid lines, map scale, or terrain elevation, which are not about the north reference difference.

Declination is the angular difference between magnetic north and true north. In navigation, maps are oriented to true north, while a compass points toward magnetic north. To make bearings from your compass usable on the map, you must adjust for this difference. If the declination is east, magnetic north is east of true north, so you add the declination to the magnetic bearing to get the true bearing. If it’s west, you subtract it. This correction is essential to keep your path aligned with the map and the real geography; without it, you’d drift off course by the size of the declination. Declination values change slowly over time as the Earth's magnetic field shifts, so updating the current local value is important. The other options describe distance between grid lines, map scale, or terrain elevation, which are not about the north reference difference.

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