Геометрия, 7 класс

http://www.treugolniki.ru/ravenstvo-ravnobedrennyx-treugolnikov/#:~:text=%D0%A0%D0%B0%D0%B2%D0%B5%D0%BD%D1%81%D1%82%D0%B2%D0%BE%20%D1%80%D0%B0%D0%B2%D0%BD%D0%BE%D0%B1%D0%B5%D0%B4%D1%80%D0%B5%D0%BD%D0%BD%D1%8B%D1%85%20%D1%82%D1%80%D0%B5%D1%83%D0%B3%D0%BE%D0%BB%D1%8C%D0%BD%D0%B8%D0%BA%D0%BE%D0%B2%20%D0%BC%D0%BE%D0%B6%D0%BD%D0%BE%20%D0%B4%D0%BE%D0%BA%D0%B0%D0%B7%D0%B0%D1%82%D1%8C%2C%20%D0%B8%D1%81%D0%BF%D0%BE%D0%BB%D1%8C%D0%B7%D1%83%D1%8F%20%D0%BF%D1%80%D0%B8%D0%B7%D0%BD%D0%B0%D0%BA%D0%B8%20%D1%80%D0%B0%D0%B2%D0%B5%D0%BD%D1%81%D1%82%D0%B2%D0%B0%20%D0%BF%D1%80%D0%BE%D0%B8%D0%B7%D0%B2%D0%BE%D0%BB%D1%8C%D0%BD%D1%8B%D1%85%20%D1%82%D1%80%D0%B5%D1%83%D0%B3%D0%BE%D0%BB%D1%8C%D0%BD%D0%B8%D0%BA%D0%BE%D0%B2.&text=%D0%95%D1%81%D0%BB%D0%B8%20%D0%BE%D1%81%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%B8%D0%B5%20%D0%B8%20%D0%B1%D0%BE%D0%BA%D0%BE%D0%B2%D0%B0%D1%8F%20%D1%81%D1%82%D0%BE%D1%80%D0%BE%D0%BD%D0%B0,%D1%82%D1%80%D0%B5%D1%83%D0%B3%D0%BE%D0%BB%D1%8C%D0%BD%D0%B8%D0%BA%D0%B0%2C%20%D1%82%D0%BE%20%D1%82%D0%B0%D0%BA%D0%B8%D0%B5%20%D1%82%D1%80%D0%B5%D1%83%D0%B3%D0%BE%D0%BB%D1%8C%D0%BD%D0%B8%D0%BA%D0%B8%20%D1%80%D0%B0%D0%B2%D0%BD%D1%8B.