First of all, we should understand what longitude is. Meridian refers to the line connecting the north and south poles on the earth's surface, also known as meridian. These lines present a straight line from the North Pole to the South Pole on the earth and are reference lines for measuring longitude and latitude.

1, and the shape of the meridian is defined as a semicircle.

The meridian is defined as a semicircle, which connects the North Pole and the South Pole. This is because only half of the meridian is visible, and the other half is hidden inside the earth and cannot be directly observed. Therefore, the meridian is not a complete circle, but a semicircle.

2. By observing a globe or a map

In addition, we can verify this fact by observing a globe or a map. On the globe or map, we can clearly see the straight line from the North Pole to the South Pole, that is, the shape of the meridian. These lines show a semicircle from the North Pole to the South Pole, not a complete circle.

3. It is proved by mathematical calculation that the shape of warp is semicircle.

In addition, we can also prove that the meridian is a semicircle by mathematical calculation. In spherical geometry, the length of warp is finite, while the length of weft is infinite. The length of longitude is the straight-line distance from the North Pole to the South Pole, while the length of latitude is the distance around the earth's surface.

The length of warp is only half that of weft.

Therefore, the length of warp yarn is only half that of weft yarn, which proves that the shape of warp yarn is semi-circular. In short, the meridian is semicircular, not a complete circle. This fact can be proved by observing globes or maps, mathematical calculations and so on. Meridian is an important reference line on the earth's surface, which is used to measure longitude and latitude. It is also an indispensable concept in geography and navigation.

Expand knowledge:

Meridians and latitudes are drawn on globes and maps to determine the position and direction on the earth. The warp and weft are perpendicular to each other. The weft is a circle with different lengths. The longest latitude is the equator. Meridian is an arc of equal length, connecting the north and south poles. Because the meridian represents the north-south direction, it is also called the meridian.