Предмет: Геометрия, автор: юлч1

Більша діагональ ромба дорівнює 12√3 см,а один з його кутів - 120°.Знайдіть сторону і меншу діагональ

Ответы

Автор ответа: myrchuk
5
Більша діагональ D = а √2 - 2 · косінус β, звідси сторона
а = D / √2 - 2 ·косінусβ = 12√3 / √2 - 2 · косінус 120 = 12√3 / √3 = 12

Менша діагональ d = а √2 + 2 · косінусβ = 12 · √2 + 2 · (- 1/2) = 12 · √ 2-1 = 12
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Упражнение 1. Поставьте глаголы в следующих предложениях в утвердительную, вопросительную и отрицательную формы Present Simple.
1. I (to do) morning exercises.
________________________
2. He (to work) at a factory.
________________________
3. She (to sleep) after dinner.
________________________
4. We (to work) part-time.
________________________
5. They (to drink) tea every day.
________________________
6. Mike (to be) a student.
________________________
7. Helen (to have) a car.
________________________
8. You (to be) a good friend.
________________________
9. You (to be) good friends.
________________________
10. It (to be) difficult to remember everything.
________________________ 4. We (to work) part-time. ________________________ 5. They (to drink) tea every day. ________________________ 6. Mike (to be) a student. ________________________ 7. Helen (to have) a car. ________________________ 8. You (to be) a good friend. ________________________ 9. You (to be) good friends. ________________________ 10. It (to be) difficult to remember everything. Упражнение 2. Раскройте скобки, употребляя глаголы в Present Simple. 1. Alice (to have) a sister. 2. Her sister’s name (to be) Ann. 3. Ann (to be) a student. 4. She (to get) up at seven o'clock. 5. She (to go) to the institute in the morning. 6. Jane (to be) fond of sports. 7. She (to do) her morning exercises every day. 8. For breakfast she (to have) two eggs, a sandwich and a cup of tea. 9. After breakfast she (to go) to the institute. 10. Sometimes she (to take) a bus. 11. It (to take) her an hour and a half to do her homework. 12. She (to speak) English well. 13. Her friends usually (to call) her at about 8 o’clock. 14. Ann (to take) a shower before going to bed. 15. She (to go) to bed at 11 p. m. Упражнение 3. Раскройте скобки, употребляя глаголы в Present Simple. 1. My working day (to begin) at six o'clock. 2. I (to get) up, (to switch) on the TV and (to brush) my teeth. 3. It (to take) me about twenty minutes. 4. I (to have) breakfast at seven o’clock. 5. I (to leave) home at half past seven. 6. I (to take) a bus to the institute. 7. It usually (to take) me about fifteen minutes to get there. 8. Classes (to begin) at eight. 9. We usually (to have) four classes a day. 10. I (to have) lunch at about 2 o’clock.
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