1.Составить во к следующим ответам.
1. I am doing my homework now.
2. They usually do their homework in the evening
3. My mother went shopping last Friday.
4. My friends have been in Italy 2 years ago.
2. Используйте глаголы в скобках в правильной форме.
1. I (has written, wrote, have written)
the letter yesterday.
2. Tamara (has, have) already (cleans, cleaned) the room.
3. I (have done, is doing, am doing) my lessons now.
4. He (has done, have done, did) his exercises till six o’clock.
Объяснение:
На пересечении (попарно) этих прямых лежат вершины треугольника.
1) Пересечение АВ и ВС: решаем систему для нахождения координат вершины В.
4x+3y-5=0 и x-3y+10 = 0.
x = 3y - 10,
4*(3y - 10) + 3y - 5 = 0;
12y - 40 + 3y - 5 = 0;
15y = 45;
y = 45/15 = 3,
x = 3*3 - 10 = 9-10 = -1.
Итак, вершина В найдена (-1; 3).
2) На пересечении прямых BC и АС, находится вершина С:
x - 3y + 10 = 0 и x-2 = 0;
x = 2;
2 - 3y + 10 = 0;
3y = 12;
y = 12/3 = 4.
Итак, координаты вершины С (2; 4).
3) На пересечении прямых AB и AC находится вершина А:
4x + 3y - 5 = 0 и x-2=0;
x=2;
4*2 + 3y - 5 = 0;
8 + 3y - 5 = 0;
3+3y = 0;
3y = -3;
y = -3/3 = -1;
Итак, координаты вершины А (2; -1).
ответ. А(2; -1), B(-1; 3), C(2; 4).
1.Составить во к следующим ответам.
1. I am doing my homework now.
2. They usually do their homework in the evening
3. My mother went shopping last Friday.
4. My friends have been in Italy 2 years ago.
2. Используйте глаголы в скобках в правильной форме.
1. I (has written, wrote, have written)
the letter yesterday.
2. Tamara (has, have) already (cleans, cleaned) the room.
3. I (have done, is doing, am doing) my lessons now.
4. He (has done, have done, did) his exercises till six o’clock.
Объяснение:
1.Составить во к следующим ответам.
1. I am doing my homework now.
2. They usually do their homework in the evening
3. My mother went shopping last Friday.
4. My friends have been in Italy 2 years ago.
2. Используйте глаголы в скобках в правильной форме.
1. I (has written, wrote, have written)
the letter yesterday.
2. Tamara (has, have) already (cleans, cleaned) the room.
3. I (have done, is doing, am doing) my lessons now.
4. He (has done, have done, did) his exercises till six o’clock.