### 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 the 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 111km At 45° latitude 79km
Important!
As the longitudes converge there is no space between them at the poles .
Eastern Hemisphere: The portion of the Earth 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.