a triangle has sides with lengths of 10ml , 24ml , and 26ml. Is it a right triangle

Answer 1

Yes.
You should have recognized this as a scaled-up version of the familiar 5-12-13 right triangle. You can save yourself some calculation by learning a few of the basic Pythagorean triples, such as
3-4-5, 5-12-13, 8-15-17, 7-24-25
and their multiples.