A.three sides measuring 9 meters, 5 meters, and 5 meters
--> only one isosceles triangle
B.three sides measuring 6 inches, 3 inches and 9 inches
--> none triangle may be formed because 9 = 3 + 6 and there is a rule (the triangle inequality theorem) that states the length of any side must be less than the sum of the lengths of other two sides.
C.three angles measuring 25°, 25°, and 130°
--> 25 + 25 + 130 = 180 => you can construct many triangles with these angles
D.three angles measuring 55°, 25°, and 125°
--> 55 + 25 + 125 = 205 > 180 => you cannot construct any triangle with theses measures.