№45 (Geometry Weekly)
Пусть O и I — соответственно центры описанной и вписанной окружности треугольника ABC. Окружности (ABC) и (AIO) пересекаются в точке A_1. Аналогично определяются точки B_1 и С_1.
Доказать, что I - ортоцентр треугольника A_1B_1C_1
BY Geometry Weekly
Most people buy Bitcoin via exchanges, such as Coinbase. Exchanges allow you to buy, sell and hold cryptocurrency, and setting up an account is similar to opening a brokerage account—you’ll need to verify your identity and provide some kind of funding source, such as a bank account or debit card. Major exchanges include Coinbase, Kraken, and Gemini. You can also buy Bitcoin at a broker like Robinhood. Regardless of where you buy your Bitcoin, you’ll need a digital wallet in which to store it. This might be what’s called a hot wallet or a cold wallet. A hot wallet (also called an online wallet) is stored by an exchange or a provider in the cloud. Providers of online wallets include Exodus, Electrum and Mycelium. A cold wallet (or mobile wallet) is an offline device used to store Bitcoin and is not connected to the Internet. Some mobile wallet options include Trezor and Ledger.
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