В треугольнике ABC{"color":"#202335","fontFamily":"stix","language":"ru"} угол 𝐶{"color":"#202335","fontFamily":"stix","language":"ru"} равен 90°{"color":"#202335","fontFamily":"stix","language":"ru"}, AB=20,AC=219.{"color":"#202335","fontFamily":"stix","language":"ru"} Найдите cosB.{"color":"#202335","fontFamily":"stix","language":"ru"}
