$ ./triangles <triangles.dat
0   3.00000   4.00000   5.00000
 THIS IS A RIGHT TRIANGLE
0   4.00000   3.00000   5.00000
 THIS IS A RIGHT TRIANGLE
0   5.00000   3.00000   4.00000
 THIS IS A RIGHT TRIANGLE
0   5.10000   3.10000   3.90000
 THIS IS NOT A RIGHT TRIANGLE
0   5.10000   3.03000   4.10000
 THIS IS A RIGHT TRIANGLE
0   8.90000   4.25000   1.40000
 THIS IS NOT A RIGHT TRIANGLE
fmt: end of file
apparent state: unit 5 (unnamed)
last format: (3F10.5)
lately reading sequential formatted external IO
Aborted