My name is Ilya. I am ten. I go to school. I am a good pupil because I always do my homework and get exсellуnt marks.
I have got a family. It is big and friendly. There are four members in my family. They are my mum, dad, brother and me.
I have got a mum. Her name is Lena. She is thirty-five. My mum is clever and kind. She is a housewife. My mum is good at cooking. Every day she cleans the rooms, washes the dishes and doesn`t let my brother and me fight.
I have got a father. His name is Dima. My father is handsome and serious. He is very busy and works a lot. My father is fond of playing computer games.At the weekends we play games together. Also, he helps me with my homework and my mum with housework. He is the best dad in the world!
My younger brother is two. His name is Vanya. He looks like my dad. Vanya is strong, clever and talented. He can swim and run. Vanya likes watching cartoons on TV. Sometimes he is naughty. He enjoys breaking my toy cars and drawing in my exercise-books. I wish I were two too
Объяснение:
Условия не достаточно. Вокруг а1b1ab можно описать окружность у которой ab -диаметр. Отрезок а1b1-равен радиусу. Угол a1bb1 равен 30 градусам (половина центрального угла). Если угол abc=сab, то abc равен 60.
Значит угол abc - любой из диапазона (30, 90) градусов.
Угол стремится к 90, когда второй угол стремится к 30, т.е. треугольник становится прямоугольным, а b1a1 его высота к гипотенузе (точки b и b1 совпадают и b1a1 равен ba/2)
Вот если треугольник не просто острый, а равнобедренный, то abc=60 градусам.
После несложных вычислений получаем: КН=36+15=51.