posted by Lola .
If the shadow of a 45 foot building is 60 feet long what time of day is it?
tan(x) = 45/60
x = 36.87°
As for the time of day, since you don't give any information on location, assume sunrise is at 6:00 am and sunset is at 6:00 pm.
In that case, 180° of arc covers 12 hours. Use that to find how many hours after 6 am (or before 6 pm) it is.