A = e*f/2 = 456 cm^2
sin(ß/2)=6/65 gibt ß=10,6°
Also Dreieck ABC hat A=0,5*sin(10,6°)*65*65=388,6
also Dreieck CDA hat A = 456-388,6 = 67,4 cm^2
andererseits A = 0,5*12*SD also SD= 11,2 cm
und dann c^2 = 6^2 + 11,2^2 also c= 12,8
also U = 2*65 + 2*12,8 = 155,6