Answer: He will need 15.24 feet of caution tape.
Step-by-step explanation:
Since we have given that
Length of door = 3 feet
Width of door = 7 feet
So, Diagonal of door is given by
[tex]sqrt{3^2+7^2}\\\\=\sqrt{9+49}\\\\=\sqrt{58}\\\\=7.62\ feet[/tex]
Since there are 2 diagonals of a rectangular door.
So, Length of caution tape he would need is given by
[tex]2\times 7.62\\\\=15.24\ feet[/tex]
Hence, He will need 15.24 feet of caution tape.