9.375
x²+9²=（12-x）²=>x=21/8，The final radius is ... 12-21/8=9.375 ? -> solution [لربع] red.lu .-. . .-.-.- .-.. ..- / ... --- .-.. ..- - .. --- -. Wide expanse for dreams and for living Are opened for us by the coming years Our loyalty to the Fatherland…