Втреугольной пирамиде sabc площадь основания abc равна 7, а углы abc, asb и двугранный угол при ребре ab равны п/2. рассматриваются проекциипирамиды sabc на всевозможные плоскости, проходящие через прямую ав.наибольшая из площадей таких проекций равна 14, а наименьшая площадь рана4 корень из 3. найти объем пирамиды.

1.You musn't throw the rubish in river

2.You must save water

3.You must teach somebody save the nature.

4.You must help janitors

5.You must help animals

6.You musn't do something which is not good for nature.

7.You musn't set a bad example

8..You musn't hunt on animals

9.You have to help keep our pollution clear

10.You must grow tress

11.You musn't throw anything in river

12You must throw batteries in special box

13.You must grow flowers

14.You musn't break trees.

15.You musn't burn grass

16.You must keep your city in purity.

17.You musn't destroy the garden

18.You musn't kill the fishes

19.You musn't smoke

20.You must follow these instructions

Pluses online lessons:
Online lessons is the perfect solution for all adults who want to learn. In general, for all those who study other than a lot of other serious responsibilities . Ability to create a flexible and convenient schedule classes.Save . Even if paid online lessons , they are still cheaper. It also saves time and effort , which is usually spent on the road to reach the conventional learning .Learning is fun and allows you to apply rich media material , whereby the absorption of the material is better.Exception of personal contact with the teacher and other students , in some cases, help get rid of psychological discomfort .Cons online lessons:
- The lack of influence of the teacher on the student , thereby losing control and efficiency of employment often .
- Mental discomfort and learning material deterioration due to lack of physical interaction . Facial expressions and gestures of the teacher , as well as his voice , too, involve memorizing material.
- The need for high-quality Internet connection to employment is not interrupted and the maximum benefit and efficiency.
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