Вычислить: 3sin0*cos50*tg40

на отрезке [ 90градусов, 900градусов ]найдите число различных корней уравнения  2cos(в квадрате)* (х+270 градусов)+3sinx=0

помогите пожалуйста!!!

запишите числа в которых:

десять десятков единиц;

десять десятков тысячь. 

 Поставьте, пожалуйста глаголы в нужном времени!

1.This bridge (build)in 1976.

2.Smoking (not allow) here.

3.The park gates (lock) a week ago.

4.The event (report) by the newspapers before they arrived home.

5.After the accident he (take) immediately home.

6.The letter (type) when I came in.

7.We think that the ship (charter) next week.

8.They will pay the money as soon as the goods (deliver).

9.The goods (not examine) yet at the custom-house. When they (examine)?

10.The question which (discuss)now at the conference is very im­portant.

11.The contract (type)before the director comes to the office.

12.Crucial scientific work (carry on)by that institute.

13.All the students (examine)by five o'clock.

14.The documents (not sign)yet by the manager. They (check)now.

15.The E-mail (deliver)in 5 minutes.