Раскрыть скобки card_total1. when i came in they (sit) round the table. mr. and mrs. brown (watch) tv while kate (read) 2. vicky ) in an italian restaurant 2 years ago.3. as soon as they (phone) me, i (tell) you. 4. ) next week.5. he (phone) me when he (get) home after work. 6. the radio ) at this moment.7. we ) in the garden at 5 yesterday.8. she (walk) along the street every week.9. the olympic games (take place) every four years. 10. you (see) that girl over there yet? she is my friend. 11. the water (boil) already.12. let's go out. look! it (not to rain) and the sun (shine) brightly. 13. vegeta¬rians (not to eat) meat. 14. he (break) his leg in a skiing accident last year. card_total15. when i came in they (sit) round the table. mr. and mrs. brown (watch) tv while kate (read) 16. vicky ) in an italian restaurant 2 years ago.17. as soon as they (phone) me, i (tell) you. 18. ) next week.19. he (phone) me when he (get) home after work. 20. the radio ) at this moment.21. we ) in the garden at 5 yesterday.22. she (walk) along the street every week.23. the olympic games (take place) every four years. 24. you (see) that girl over there yet? she is my friend. 25. the water (boil) already.26. let's go out. look! it (not to rain) and the sun (shine) brightly. 27. vegeta¬rians (not to eat) meat. 28. he (break) his leg in a skiing accident last year.
Проведем из вершины В треугольника АВС высоту ВН к основанию АС.
Так как, по условию, АВ = ВС, то треугольник АВС равнобедренный, а высота ВН в равнобедренном треугольника, так же является и медианой. Тогда АД = СД = АС / 2 = 12 / 2 = 6 см.
Рассмотрим прямоугольный треугольник АВД, и по теореме Пифагора определим длину катета ВН.
ВН2 = АВ2 – АД2 = 100 – 36 = 64.
ВН = 8 см.
Рассмотрим треугольный треугольник ДВН и по теореме Пифагора определим длину гипотенузы ДН.
ДН2 = ДВ2 + ВН2 = 152 + 82 = 225 + 64 = 289.
ДН = 17 см.
ответ: Расстояние от точки Д до прямой АС равно 17 см.
Объяснение:
Дано:
<AOB и <COD
<COD внутри <AOB
AO ┴ OD; CO ┴ OB;
<AOB - <COD = 90°
Найти: <AOB и <COD.
Решение
Т.к . AO ┴ OD; CO ┴ OB,
то <AOD = 90; <COB = 90°.
<COD = <AOD - <AOC
<COD = <COB - <DOB
<COD = 90° - <AOC
<COD = 90° - <DOB
Получим
<AOC = 90° - <COD
<DOB = 90° - <COD
Следовательно <AOC = <DOB
2) По условию: <AOB - <COD = 90°
Но если от всего угла <AOB отнять <COD, то останутся два равных угла <AOC и <DOB, значит, это их сумма равна 90°.
<AOC + <DOB = 90° =>
<AOC = <DOB = 90°/2 = 45°
3) <COD = 90° - <DOB
<COD = 90° - 45°=45°
4) <AOB = <AOC + <DOB + <DOB
<AOB = 45° + 45° + 45° = 135°
ответ: <AOB - 135°; <COD =45°.