Consider the following lines of Longitude and Latitude:
1.Prime Meridian
2.Tropic of Cancer
3.Equator
Which of the above lines is/are a Great Circle?

The correct answer is 3 only.

Key Points

• A Great Circle is the largest possible circle that can be drawn on a sphere, dividing it into two equal hemispheres.
• The Equator is a Great Circle because it divides the Earth into the Northern and Southern Hemispheres.
• The Prime Meridian is not a Great Circle as it does not divide the Earth into two equal hemispheres. It is a longitudinal line running from the North Pole to the South Pole.
• The Tropic of Cancer is not a Great Circle as it is a parallel of latitude located north of the Equator, and its circumference is smaller than that of the Earth.
• Hence, among the given options, only the Equator qualifies as a Great Circle.

Additional Information

• Great Circle Definition: A Great Circle is formed when a plane passes through the center of a sphere, creating the largest possible circle on its surface.
• Examples of Great Circles: The Equator is the only latitude line that is a Great Circle. All longitudinal lines (e.g., Prime Meridian) form half of a Great Circle when paired with their opposite meridian.
• Importance in Navigation: Great Circles are used in navigation and aviation to find the shortest path between two points on Earth's surface.
• Tropic of Cancer and Tropic of Capricorn: These are parallels of latitude located at 23.5°N and 23.5°S, respectively, and are not Great Circles since they do not divide the Earth into two equal halves.
• Prime Meridian: It is the 0° longitude line that runs through Greenwich, England, but it only forms a semicircle by itself and thus is not a Great Circle.