реши tg2α+ctg2α,если tgα+ctgα=3 2-вторая степень

Как решить эти 2 номера, только с объяснением, чтобы было все понятно?

о чем меня заставили задуматься рассказы чехова

Change the following sentences into Passive Voice:

1.They are building a bridge here.

2.They didn't inform us.

3.She looks after the children very well.

4.People must wear ties in this club.

5.They make a new film every year in this studio.

6.He didn't introduce me to his mother.

7.They will meet you at the terminal.

8.You may not use dictionaries during the examination.

9.A big truck knocked him down last Monday.

10.they are renovating the castle at the moment.