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?

A Great Circle is any circle drawn on a sphere whose center coincides with the center of the sphere, dividing it into two equal hemispheres. The Equator is the only line of latitude that is a Great Circle because it passes through the center of the Earth and divides it into Northern and Southern Hemispheres equally. All meridians (lines of longitude), including the Prime Meridian, are halves of great circles, and a meridian paired with its antimeridian (180° opposite) forms a complete Great Circle. Therefore, both the Prime Meridian and the Equator are Great Circles. The Tropic of Cancer is a small circle, not a Great Circle, because it does not pass through the Earth's center.