Задача. Высоты 𝐵𝐵₁ и 𝐶𝐶₁ остроугольного треугольника 𝐴𝐵𝐶 пересекаются в точке 𝐻. Пусть 𝐵₂ и 𝐶₂ — точки на отрезках 𝐵𝐻 и 𝐶𝐻 соответственно такие, что 𝐵𝐵₂ = 𝐵₁𝐻 и 𝐶𝐶₂ = 𝐶₁𝐻. Описанная окружность треугольника 𝐵₂𝐻𝐶₂ пересекает описанную окружность треугольника 𝐴𝐵𝐶 в точках 𝐷 и 𝐸. Докажите, что треугольник 𝐷𝐸𝐻 прямоугольный.
Задача. Высоты 𝐵𝐵₁ и 𝐶𝐶₁ остроугольного треугольника 𝐴𝐵𝐶 пересекаются в точке 𝐻. Пусть 𝐵₂ и 𝐶₂ — точки на отрезках 𝐵𝐻 и 𝐶𝐻 соответственно такие, что 𝐵𝐵₂ = 𝐵₁𝐻 и 𝐶𝐶₂ = 𝐶₁𝐻. Описанная окружность треугольника 𝐵₂𝐻𝐶₂ пересекает описанную окружность треугольника 𝐴𝐵𝐶 в точках 𝐷 и 𝐸. Докажите, что треугольник 𝐷𝐸𝐻 прямоугольный.
For example, WhatsApp restricted the number of times a user could forward something, and developed automated systems that detect and flag objectionable content. The original Telegram channel has expanded into a web of accounts for different locations, including specific pages made for individual Russian cities. There's also an English-language website, which states it is owned by the people who run the Telegram channels. This provided opportunity to their linked entities to offload their shares at higher prices and make significant profits at the cost of unsuspecting retail investors. On February 27th, Durov posted that Channels were becoming a source of unverified information and that the company lacks the ability to check on their veracity. He urged users to be mistrustful of the things shared on Channels, and initially threatened to block the feature in the countries involved for the length of the war, saying that he didn’t want Telegram to be used to aggravate conflict or incite ethnic hatred. He did, however, walk back this plan when it became clear that they had also become a vital communications tool for Ukrainian officials and citizens to help coordinate their resistance and evacuations. As the war in Ukraine rages, the messaging app Telegram has emerged as the go-to place for unfiltered live war updates for both Ukrainian refugees and increasingly isolated Russians alike.
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