Нехай 𝑂 та 𝐻 — центр описаного кола та ортоцентр гострокутного трикутника 𝐴𝐵𝐶. На сторонах 𝐴𝐶 та 𝐴𝐵 відмітили точки 𝐷 та 𝐸 відповідно так, що відрізок 𝐷𝐸 проходить через точку 𝑂 та 𝐷𝐸||𝐵𝐶. На стороні 𝐵𝐶 обрали точки 𝑋 та 𝑌 такі, що 𝐵𝑋 = 𝑂𝐷 та 𝐶𝑌 = 𝑂𝐸. Доведіть, що ∠𝑋𝐻𝑌 + 2∠𝐵𝐴𝐶 = 180°.
Нехай 𝑂 та 𝐻 — центр описаного кола та ортоцентр гострокутного трикутника 𝐴𝐵𝐶. На сторонах 𝐴𝐶 та 𝐴𝐵 відмітили точки 𝐷 та 𝐸 відповідно так, що відрізок 𝐷𝐸 проходить через точку 𝑂 та 𝐷𝐸||𝐵𝐶. На стороні 𝐵𝐶 обрали точки 𝑋 та 𝑌 такі, що 𝐵𝑋 = 𝑂𝐷 та 𝐶𝑌 = 𝑂𝐸. Доведіть, що ∠𝑋𝐻𝑌 + 2∠𝐵𝐴𝐶 = 180°.
The War on Fakes channel has repeatedly attempted to push conspiracies that footage from Ukraine is somehow being falsified. One post on the channel from February 24 claimed without evidence that a widely viewed photo of a Ukrainian woman injured in an airstrike in the city of Chuhuiv was doctored and that the woman was seen in a different photo days later without injuries. The post, which has over 600,000 views, also baselessly claimed that the woman's blood was actually makeup or grape juice. Individual messages can be fully encrypted. But the user has to turn on that function. It's not automatic, as it is on Signal and WhatsApp. As a result, the pandemic saw many newcomers to Telegram, including prominent anti-vaccine activists who used the app's hands-off approach to share false information on shots, a study from the Institute for Strategic Dialogue shows. "Your messages about the movement of the enemy through the official chatbot … bring new trophies every day," the government agency tweeted. Despite Telegram's origins, its approach to users' security has privacy advocates worried.
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