1.найдите координаты и длину вектора AC? если А(1;-2) С(6;10) 
2.Найдите площадь параллелограмма ABCD,если AB=6,5, AC=8 см , а угол А =45 градусов. 
3.Найти радиус окружности, если ее длина равна 8,2Pi см. 
4.Найдите площадь круга ,радиус которого равен 10 дм

Не могу решить 3 задания! Срочно надо! Спасибо заранее!

--

1)В параллелограмме ABCD диагонали пересекаются в точке O, угол BOC=140 градусов, угол CAD=10 градусов и BD=2AB.Найдите углы параллелограмма.

--

2)В равнобедренной тропеции ABCD с основанием BC и AD угол B равен 120 градусам, BC=6, AD=14. Найдите боковую сторону тропеции.

--

3)В прямоугольной тропеции меньшее основание равно 9, меньшая диагональ 15. Найдите угол между этой диагональю и большей боковой стороной, которая равна 20.

--

P.s: 1 и 2 просто ответ, а вот к 3 надо прям решение))

Проверьте отрывок из эссе, пожалуйста.

I've recently read a book, which has made a very deep impression on me. It is named "The Pillars of the Earth". The author of the book is Ken Follett. I've never been a fan of Follett, and picked this book up with some misgivings - this book was adapted for TV series. But Follett does an amazing job of both presenting a realistic picture of the period and connecting the characters so closely, that the 2 threads are interwoven, instead of one outshining the other. What makes The Pillars of the Earth extraordinary is the time—the twelfth century; the place—feudal England; and the subject—the building of a glorious cathedral. The building of the cathedral serves as a cornerstone to explore the lives of an intriguing cast of characters and how life was lived at that point in history. What made the book for me was the characters. Even the protagonists had flaws that were believable. They persevered despite their flaws and in some cases even tried to overcome them. But each character revealed something of twelfth century life. There was the monk, the young woman, the builder, the earl, and minor roles for figures from history. They all added something to the story, and they each felt like a real person. I would advise you to read this book.