Задача. Про выпуклый пятиугольник 𝑅𝐴𝐷𝑂𝑆 известно, что 𝑅𝑆 = 𝑆𝑂 и ∠𝐴𝑅𝑆 = ∠𝐷𝑂𝑆 = 90°. Внутри 𝑅𝐴𝐷𝑂𝑆 взята точка 𝑇 так, что 𝑅𝑇 ⊥ 𝐴𝑆 и 𝑇𝑂 ⊥ 𝐷𝑆. Докажите, что 𝑆𝑇 ⊥ 𝐴𝐷.
Задача. Про выпуклый пятиугольник 𝑅𝐴𝐷𝑂𝑆 известно, что 𝑅𝑆 = 𝑆𝑂 и ∠𝐴𝑅𝑆 = ∠𝐷𝑂𝑆 = 90°. Внутри 𝑅𝐴𝐷𝑂𝑆 взята точка 𝑇 так, что 𝑅𝑇 ⊥ 𝐴𝑆 и 𝑇𝑂 ⊥ 𝐷𝑆. Докажите, что 𝑆𝑇 ⊥ 𝐴𝐷.
Apparently upbeat developments in Russia's discussions with Ukraine helped at least temporarily send investors back into risk assets. Russian President Vladimir Putin said during a meeting with his Belarusian counterpart Alexander Lukashenko that there were "certain positive developments" occurring in the talks with Ukraine, according to a transcript of their meeting. Putin added that discussions were happening "almost on a daily basis." 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. This ability to mix the public and the private, as well as the ability to use bots to engage with users has proved to be problematic. In early 2021, a database selling phone numbers pulled from Facebook was selling numbers for $20 per lookup. Similarly, security researchers found a network of deepfake bots on the platform that were generating images of people submitted by users to create non-consensual imagery, some of which involved children. Investors took profits on Friday while they could ahead of the weekend, explained Tom Essaye, founder of Sevens Report Research. Saturday and Sunday could easily bring unfortunate news on the war front—and traders would rather be able to sell any recent winnings at Friday’s earlier prices than wait for a potentially lower price at Monday’s open. "Like the bombing of the maternity ward in Mariupol," he said, "Even before it hits the news, you see the videos on the Telegram channels."
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