Asnswer:
Step-by-step explanation:
Firstly we calculate length of CB
/CA/^2 = /BA/^2 + /CB/^2
12^2 = 6^2 + /CB/^2
144 = 36 + /CB/^2
/CB/^2 = 144 - 36
/CB/^2 = 108
/CB/ = √108
/CB/ = 10.4cm
Sin55 = (/CB/)/(/CD/)
Sin55 = 10.4/(/CD/)
/CD/ = 10.4/sin55
/CD/ = 12.7cm
