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6. При виконанні тахеометричного і теодолітного знімання в
геодезії використовують полярну систему координат.

V. SPEAKING

Task 1. Read the text and say, what are the basic elements of
a geographic coordinate system. Prove your answer with the
sentences from the text.

Geographic coordinate system

The geographic coordinate system is based on a set of imaginery
lines that intersect one another and encompass the Earth’s surface.

Determining location and direction using this system is based on two
key lines - the prime meridian and the equator.
Geographic coordinates are useful in determining location and

orientation and identifying changes in location or relative distance
between points on a spheroidal surface. The concept of latitude and
longitude and vertical distance the above the geoid is the basis for any
expression of geographic coordinates on the Earth’s surface.

The basic elements of a geographic coordinate system are:
- Equator is formed by the intersection of a plain bisection of the
Earth at right angles to the axis of rotation.

- Meridians are formed by the intersection of vertical planes
passing through the center of the Earth and the sphere or spheroid
(ellipsoid). The prime meridian passes through the Royal Observatory

at Greenwich, England. This base meridian is now internationally
recognized.
- Latitude and longitude are defined using an ellipsoid, an ellipse

rotated about an axis. Latitude is measured in degrees north or south
of the equator. Longitude is measured in degrees west or east of the
prime meridian
- Elevation defined using geoid, a surface of constant gravitational

potential.
- Earth datums define standard baseline values of the ellipsoid and
geoid.

In spatial information and mapping software, like GIS, it is easier
to use decimal degrees (DD) than degrees, minutes, and seconds
(DMS) to represent geographic coordinates. Letters like “E” and “W”
are used define locations east and west of the prime meridian,

respectively, in each hemisphere. In the decimal degree system,

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