В треугольнике ABC {"color":"#202335","fontFamily":"stix","language":"ru"}известно, что AB=5,{"color":"#202335","fontFamily":"stix","language":"ru"} BC=10,{"color":"#202335","fontFamily":"stix","language":"ru"} AC=11.{"color":"#202335","fontFamily":"stix","language":"ru"} Найдите cos∠ABC.{"color":"#202335","fontFamily":"stix","language":"ru"}
