Пусть △ABC — остроугольный треугольник с описанной окружностью ω. Высоты AD, BE и CF треугольника ABC пересекаются в точке H. Точка K выбрана на прямой EF так, что KH и BC параллельны. Докажите, что точка, симметричная H относительно прямой KD, лежит на ω.
Пусть △ABC — остроугольный треугольник с описанной окружностью ω. Высоты AD, BE и CF треугольника ABC пересекаются в точке H. Точка K выбрана на прямой EF так, что KH и BC параллельны. Докажите, что точка, симметричная H относительно прямой KD, лежит на ω.
"Your messages about the movement of the enemy through the official chatbot … bring new trophies every day," the government agency tweeted. Two days after Russia invaded Ukraine, an account on the Telegram messaging platform posing as President Volodymyr Zelenskiy urged his armed forces to surrender. In a message on his Telegram channel recently recounting the episode, Durov wrote: "I lost my company and my home, but would do it again – without hesitation." 'Wild West' At its heart, Telegram is little more than a messaging app like WhatsApp or Signal. But it also offers open channels that enable a single user, or a group of users, to communicate with large numbers in a method similar to a Twitter account. This has proven to be both a blessing and a curse for Telegram and its users, since these channels can be used for both good and ill. Right now, as Wired reports, the app is a key way for Ukrainians to receive updates from the government during the invasion.
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