Yes, I do. I with my family celebrate it every year. We like this holiday, because it is very funny and smiley. One of the oldest tradition in ourr family is when we make many pancakes on Maslenitsa!
Рассмотрим ΔAOB и ΔCOD:
AB = CD (по условию)
∠ABO = ∠OCD (как накрест лежащие при AB║CD и CB - секущая)
∠BAO = ∠CDO (как накрест лежащие при AB║CD и AD - секущая)
ΔAOB = ΔCOD (по стороне и прилежащим к ней углам) ⇒ AO = CO, ч.т.д.
1. 2/10
2. 1 21/100
3. 87/1000