Exercise 1 solution

Answers depend on your location, so this is a method, not a number.
1. Find a table of sun times and sun elevation for your location (for example a sunrise/sunset site that lists civil twilight and sun altitude).
2. Note the time of sunrise and the time the sun reaches 6 degrees altitude. The difference is your golden-hour length after sunrise under the "0 to 6 degrees" definition.
3. Repeat for another season. The chapter's source says the period is not fixed and depends on season and latitude: farther from the equator it is longer, and at high latitudes it can last all day in some seasons.
Write down which source and which definition you used, since the article gives several definitions.