West
The Cook Islands of New Zealand are on the east side of the International Date Line, 10 hours behind UTC (the same time offset as Hawaii).
they are all located in the east and west side of the southern hemisphere divided by the international date line
Samoa and Tonga to the west of the Cook Islands, and Tahiti to the east. Aotearoa New Zealand lie south of the Cook Islands.
The International Date Line generally follows the "anti-meridian" at 180 degrees of longitude. However, it deviates east and west in a very political fashion, to keep most of the islands near the 180 mark in the same day. So around the Aleutian islands of Alaska, the International Date Line cuts way over to the west, to keep all of the Aleutian Islands on the same day.
Samoa is located just east of the International Date Line. This positioning is significant because in 2011, Samoa shifted to the west of the date line to align its time zone with other Pacific islands.
Alaska, USA is just east of the International Date Line.
The meridian at latitude 180 generally coincides with the International Date Line, but the International Date Line zigs and zags to keep nations within the same day. So for example, the Aleutian Islands stretching westward from Alaska are all on the same "day", even the islands which are in east longitude.
The closest continent east of the International Date Line is North America.
If it is Thursday on the west side of the International Date Line, what day is it on the east side?
The International Date Line is the meridian where the date changes by one day when crossed east to west. This happens in order to account for the time difference between different parts of the world. Crossing the International Date Line from east to west, you "gain" a day, and crossing from west to east, you "lose" a day.
If it is Thursday on the west side of the International Date Line, what day is it on the east side?
French Polynesia is located to the east of the International Date Line, primarily observing the UTC-10:00 time zone. However, some of its islands, such as the Marquesas Islands, are on UTC-9:30. As a result, French Polynesia has a unique time configuration that can vary between its different islands.