Answer:
not a right triangle
Explanation:
The side lengths of a right triangle will satisfy the relation given by the Pythagorean theorem:
c² = a² +b²
23² = 14² +19²
529 = 196 +361
529 = 557 . . . . . . . . not true; not a right triangle
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The longest side (23 mm) is too short for a right triangle, so the angle opposite will be smaller than 90°. This is an acute triangle.
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If you're doing a bunch of these comparisons, use of a triangle solver app or spreadsheet can help.