Answer:
About 14
Step-by-step explanation:
The diagonal BD is the hypotenuse of the triangol ΔBCD. You can find the lenght of the side BC (BC = BD × cos α = 5 × cos 45° = 3.54) or the lenght of the side CD (CD = BD × sin α = 5 × sin 45° = 3.54). Now you can multiply 3.54 by four to find the perimeter (P = 3.54 × 4 = 14.16).
Answer: 14.16 (I don't know the unit of measurement).
I hope I helped you :D
