in the abcd parallelogram ad=10 units ab= 8 units ac=12 units ed= 4.5 units bd=

Answer 1

using the law of cosines,

12^2 = 10^2 + 8^2 + 2*10*8 cosθ = 164+160cosθ
BD^2 = 10^2 + 8^2 - 2*8*10 cosθ
= 164 - 160(-20/160) = 184
BD = 13.56