모루겠어요ㅠㅠ
a에서 bc에 수선을 내려 h.
bh = 2. ah = 2루트3. bc = 2+6+2 = 10.
abcd = (6+10)*2루트3*1/2 = 16루트3.
ac^2 = ah^2 + ch^2 = 12 + 64 = 76.
abcd = ac*bd*sin(각ced)*1/2
= ac^2*sin( 각ced)*1/2
= 38*sin(각ced) = 16루트3
sin(각ced) = (16루트3)/38 = (8루트3)/19