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=5,AC=21{"color":"#202335","fontFamily":"stix","language":"ru"}. Найдите sinA{"color":"#202335","fontFamily":"stix","language":"ru"}.
