Answer: 12.66
Step-by-step explanation:
Use pytagoras to find CB
AB= 6 cm
CA=12 cm
CB²=CA²-AB²
CB²=12²-6²
CB²=144-36
CB=√108
CB=6√3
Using formula for sinα=CB/CD
α=55°
sin55°=6√3/CD
CD=6√3/sin55°
CD= 6*1.73/0.82=10.38/0.82=12.66
