Explanation: Understanding the geographical coordinates of a state like Arunachal Pradesh is crucial for various geographical and administrative purposes. The longitude of a place is one of the two coordinates used to specify its exact location on the Earth's surface, the other being latitude. The longitude is measured in degrees east or west from the Prime Meridian, which is an imaginary line that runs from the North Pole to the South Pole and passes through the Royal Observatory in Greenwich, England.
In the case of Arunachal Pradesh, its longitude is 97$^\circ$25'E. This means that the state is located 97 degrees and 25 minutes east of the Prime Meridian. The 'E' in the coordinate indicates that the longitude is east of the Prime Meridian. The use of degrees and minutes (and sometimes seconds) allows for a precise specification of a location's position on the Earth.
It is important to note that the longitude of a place can be used in conjunction with its latitude to pinpoint its exact location. For example, the latitude of Arunachal Pradesh is approximately 28$^\circ$N, which means it is located 28 degrees north of the Equator. Together, these coordinates provide a complete and accurate geographical reference for the state.
Understanding these coordinates is essential for various applications, including navigation, mapping, and administrative purposes. For instance, in the context of competitive examinations such as the UPSC Civil Services or State PSC Exams, knowledge of the geographical coordinates of different states is often tested to assess a candidate's understanding of basic geographical concepts and their ability to locate places accurately on a map.
In summary, the longitude of Arunachal Pradesh is 97$^\circ$25'E, which is a precise and accurate representation of the state's longitudinal position on the Earth's surface. This information is crucial for geographical and administrative purposes and is a key piece of knowledge for students and professionals alike.