Отрезки АС и BD пересекаются в точке О,  ОА=ОВ и ОС=ОD. Докажите, что АD=ВС. Помогите(((

write the questions 

1. where                  ?

tom and jess are in blackdown house

2. whose                 ?

the children's mother is worried

3. how many          ? 

they can see three people 

4. what                    ?

the servants want the key to the secret room

5. why                      ?

they want  to go into the secret room because  there is gold in it   

6.how much            ?

there's a lot of gold in the secret room