I can't seem to figure out the most simple word problem, I keep getting stuck at the end.

Question

"A local businessman bought a square plot of land. The sides of the lot measure 100 feet on each side. He puts a fence around the entire plot and he decides to split the lot into two equal-sized right triangles by putting a fence down the diagonal. Approximately how many feet of fencing will he need to fence in both sections? Round your answer to the tenths place and do not include a label."

Answer 1

100 feet for each side of a square with 400 feet of fencing to enclose it

he cuts the square down the middle diagonally with two separat right triangle areas, a fence of 100sqr2 down the middle

how much total fence does he now need? 400 + 100sqr2 = about 541.6 feet