Предмет: Геометрия, автор: AverkovichYana

срочно! нужен полный ход решения, 8 класс

Приложения:

AverkovichYana: спасибо большое)

Ответы

Автор ответа: siestarjoki
3

AO=BO (радиусы), AOB - равнобедренный

OE - высота и медиана, AE=EB

AOE - египетский, множитель 2, AE=6

AB=2AE=2*6=12

Аналогично CD=2CF=2*8=16

Концы хорды равноудалены от центра окружности, следовательно центр окружности лежит на серединном перпендикуляре к хорде.


siestarjoki: Или G - точка пересечения хорд. OEGF - прямоугольник, его диагональ по теореме Пифагора равна радиусу (=10) - точка G лежит на окружности (G, D, B совпадают). Угол AGC - прямой, AC - диаметр. OE, OF - средние линии в AGC, стороны вдвое больше.
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Определите, верны, ли утверждения

Существуют три прямые, которые проходят через одну точку.
Да
Нет

Через заданную точку плоскости можно провести единственную прямую.
Да
Нет

Смежные углы всегда равны.
Да
Нет

Угол между биссектрисами вертикальных углов равен 180 градусов.
Да
Нет

Если угол острый, то смежный с ним угол также является острым.
Да
Нет

Вертикальные углы всегда равны.
Да
Нет

Выберите правильный ответ

Сколько прямых можно провести через любые две точки?
много
одну и только одну
две

Как называется угол в 180 градусов?
прямой
развернутый
острый
тупой
вертикальный

Что называется биссектрисой угла?
луч, делящий угол пополам
луч, исходящий из вершины угла и делящий его на два равных угла
луч, делящий треугольник пополам
луч, делящий противоположную сторону пополам

Чему равна сумма смежных углов?
180
90
360
190

При пересечении двух прямых образовались четыре угла, сумма трех из которых равна 270 градусов. Найдите все получившиеся углы.
60, 120, 60, 120
90, 90, 90, 90
60, 60, 60, 60