Answer: About 27.01
Step-by-step explanation: The way to find the diagonal is to multiply one side of the square by the sq. rt. of 2. First, we had to find one side of the square, which would be 76.4 divided by 4, then multiply that by the square root of 2.
76.4 / 4 = 19.1
19.1 x sq. rt. of 2 = 27.0114790413, or about 27.01