How to calculate the geographical time zone?

How to calculate the geographical time zone?

Area time = known area time + / - time difference between two places (the east side of the known area is added and the west side is subtracted)
The calculation of time difference is: in the same east time zone (West time zone), the time difference is equal to the area code subtraction; in case of one east and one west, the area code subtraction
For example: it is known that the time of the East eight districts is 9:00, and the time of the East eleven districts and the West three districts is calculated?
East 11: 9 + (11-8) = 11:00
West District 3: 9 - (8 + 3) = (- 2), time is not negative, so - 2 + 24 means 22:00 the day before

The formula of geographical time zone and district time in senior one
I'm absent from class for some reasons. Who can make it clear to me? Thank you. It's easier to understand

Based on the prime meridian (zero degree longitude), every 15 ° to the East and West is a time zone, then the difference of 1 ° is 4 minutes. The world can be divided into 24 time zones;
The time to the East should be increased and the time to the West should be decreased (except near the international date change line, when crossing the international date change line from west to East, one day should be decreased, and when crossing the international date change line from east to west, one day should be increased);
If the result is negative, subtract one day and then add 24 hours;
Local time is calculated based on the local longitude. Area time is the common reference time within 15 longitudes of a time zone. The difference is one hour every 15 degrees
Local time = local time - (longitude to the right of time zone - local longitude) X4 minutes
The middle line of time zone is 7.5 degrees (half of 15 degrees of a time zone)!

How to calculate area time
Please give an example to explain,

There is no London in America. London is in England
Just know the time zone of the place you want to calculate. Add to the East and subtract from the West. For example, London is in the 0 time zone, and Beijing is in the 8 East districts, so Beijing is eight hours faster than London

What's the district time
Wusu town is the easternmost village in China. The sunrise can be seen at about 2:15 a.m. every year. At this time, the time zone of Wuqia county (39 ° 15'n, 73 ° 33'e) in the westernmost part of China is about?

23：15
The former is Beijing time, i.e. East eight district time
Wuqia county (73 ° 33'e) is the East five District, three hours later than the East eight district

Calculation of zone time
It is said in the book that the calculation method of district time is: the time zone to be calculated = known District time - (the time zone of known District time - the time zone to be calculated), then the known Beijing time is 15:00, which is a 12 hour system, and Beijing is the East 8 District. What is the district time of Beijing? (the known quantities are all written up, I don't know if it is helpful for calculation, I don't know anything about it.) please write down the specific calculation steps, known District time, What do you mean by the time zone height of the known zone time and the zone time to be calculated?

Area time to be calculated (not time zone) = known area time - (time zone of known area time - time zone of area time to be calculated)
(Note: East time zone is positive, west time zone is negative)
Area time to be calculated: local time of place B (e.g. New York) to be calculated
Known District time: the local time of known place a (such as 15:00 Beijing time)
Time zone of known zone time: the time zone of Beijing is the eighth East Zone, and the eighth east zone here is the time zone of known zone time
Time zone to calculate zone time: New York's time zone is west five, and the west five here is "time zone to calculate zone time."
So Beijing time is 15:00, New York local time is 15:00 - (8 - (- 5)) = 2:00

How to calculate the district time?

1.1 area is 1 hour, 15 longitudes
Because the earth rotates from west to East, the time in the East is always ahead of that in the West
180 ° is the international date change line
4.0 is also the international date change line. Before is the previous day, after is the next day

How to calculate the area time
What is the longitude of a place at noon and 12:16 Beijing time?

116 degrees east longitude
Fifteen degrees an hour, one degree four minutes

I always don't understand the conversion of geographical area time and the coordinates of direct sunlight
For example, 5:00 p.m. Beijing time on the 8th, Washington (West District 5) time
The answer given in the textbook is (12 + 5) - 13 = 4
Why use 12 + 5, why - 13
And the time of the East eight districts is 8:35 on May 1, and the time of the West nine districts
The answer is 8:35 on May 1st - 1 day + (12-8) + (12-9) = 15:35 on April 30th
I calculate the first problem with the algorithm of the second problem,

For example, at 5:00 p.m. Beijing time on the 8th, the answer given by the time textbook of Washington (West District 5) is (12 + 5) - 13 = 4. The reason is that Washington (West District 5) "is located to the west of Beijing (East District 8)", and the time should be 13 hours later than Beijing

Time conversion of geographical area and day range judgment of the same date
Seattle time (Western District 8. Local daylight saving time, that is, one hour earlier than District time) at 10:50 on April 18, Beijing time is on the equator at this time, which belongs to the eastern hemisphere and is on the same day as Seattle

① Because Seattle adopts daylight saving time, which is one hour earlier than the district time, the district time is 9:50 on April 18. That is to say, the district time of the eighth west district is 9:50 on April 18. Beijing is the eighth East District, and the difference between the eighth west district and the eighth East District is 16 hours

It is known that 8:00 on March 2, 2008 in East eight district, which is 10 hours and 16 minutes earlier than a certain place

How to write the process. In the West six districts, the longitude is 86 degrees west longitude, and the central longitude is 90 degrees west longitude. The district time is 18:00 on March 27, and the local time is 18:16