3)11
Объяснение:
АВСДА1В1С1Д1 - усеченная пирамида , в основаниях квадраты АВСД со стороной =10, А1В1С1Д1 со стороной=2, ОО1-высота пирамиды=7, АС=корень(АД в квадрате+СД в квадрате)=корень(100+100)=10*корень2, А1С1=корень(А1Д1 в квадрате+С1Д1 в квадрате)=корень(4+4)=2*корень2,
рассматриваем АА1С1С как равнобокую трапецию, АА1=СС1, проводим высоты А1К и С1Н на АС, КА1С1С-прямоугольник А1С1=КН=2*корень2, А1К=С1Н=ОО1=7-высота, треугольник АА1К=треугольник НС1С как прямоугольные по гипотенузе и катету, АК=СН=(АС-КН)/2=(10*корень2-2*корень2)/2=4*корень2
АН=АК+КН=4*корень2+2*корень2=6*корень2, треугольник АС1Н прямоугольный, АС1-диагональ пирамиды=корень(АН в квадрате+С1Н в квадрате)=корень(72+49)=11
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: