Me! can a triangle have sides with the given lengths? 5 ft, 6 ft, 13 fta. yes, because 5 + 6 < 13 satisfies the triangle inequality theorem. b. no, because 5 + 6 < 13 contradicts the triangle inequality theorem. c. yes, because 13 + 5 > 6 satisfies the triangle inequality theorem. d. no, because 13 + 5 > 6 contradicts the triangle inequality theorem.

Check the picture below.

notice the sides, now, on the second triangle, side 6 slants a bit more to fit in 13, on the third triangle, side 6 slants even further to fit 13 in, now, if 6 were to slant completely, it'll make a flat-line with side 5, and there will be a triangle no more.

but even if side 6 would stretch to a flat-line, 5+6 is just 11, whilst side 13 is longer than that, so no dice.