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:
35113996
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Без лишних слов ( эмоции )
R₁ =3√3* √3 /3 = 3 * * * R =(a√3/2)*2/3 =(a√3)/3 * * *
R₂ =4√3* √3 /3 = 4
R₁² = x (2R - x) ⇔x² - 2Rx + 9 = 0 ⇒ x₁ =R -√(R²- 9)
Маленький кусок диаметра x₁ =12 (между основания со стороной 3√3 и поверхностью шара) ( большой кусок x₂=R+ -√(R²- 9) )
Аналогично
R₂² = y (2R -y) ⇔ y² - 2Ry + 16=0 ⇒ y ₁ = R -√(R²- 16 )
x₁+ H + y₁ = 2R ⇔ R -√(R²- 9) + 7 + R -√(R²- 16) = 2R ⇔
R -√(R²- 9) + 7 + R -√(R²- 16) =2R ;
√(R²- 9) + √(R²- 16) =7 * * * ясно R =5 * * *
для сомневающихся (неужели нет другое решение ?)
примитивное иррациональное уравнение
необязательная замена t =R² > 0
√(t- 16) = 7 -√(t - 9) ⇔ t- 16 =49 -14√(t - 9) + t -9⇔ 14√(t - 9) =56 ⇔
t - 9 = 4² ⇔ t =25
R² =25 ⇒ R = 5 ( R = -5 построенное решение )
ответ : 5 см .
Изменение
добавил неповторимый пейзаж