Please have a look at diagram attached.
We can use Pythagorean theorem to find lenght of each wire.
x^2 = 16^2 + 12^2
x^2 = 256 + 144
x^2 = 400
x = 20
Lenght of one wire is 20
Hence lenght of two wires would be 20 * 2 = 40 feet : Answer
Hope it will help you :)