### Theory:

Longitudes
• Imaginary lines
• Sketched vertically, connecting the North Pole and the South Pole.
• They are also called lines or meridians of longitude.
• These lines of longitude are seen as semi-circles.
Degrees of longitudes can be divided into minutes, and each minute of longitude can be further divided into seconds.
Important!
$$1°$$ (degree) $$=$$$$60$$' (minutes)
$$1'$$(minute) $$=$$$$60$$'' (seconds)

Important!
Prime Meridian: $$0°$$ line of longitude
Number of lines on either side of Prime meridian: $$180$$ lines of longitude
Total lines of longitude: $$360$$ lines.
• These lines converge at the poles.
• The $$180°$$ W and $$180°$$ E line of longitude are the same line.
• Eastern Longitudes: The lines of longitude found between the Prime Meridian($$0°$$) and the$$180°$$East line of longitude.
• Western Longitudes: The lines of longitude found between the Prime Meridian ($$0°$$) and the$$180°$$ West line of longitude.
Two opposite meridians form a great circle.
The lines of longitude are
 At Equator: Semi circles covering $$111$$ km At $$45°$$ latitude $$79$$ km
Important!
As the longitudes converge there is no space between them at the poles .
Eastern Hemisphere: The portion of the Earth that lies between the $$0°$$ line of longitude and the $$180°$$East line of longitude.

Western Hemisphere: The portion of the Earth that lies between  $$0°$$ line of longitude to $$180°$$West line of longitude.