To determine the type of triangle formed by the sides measuring 3 cm, 5 cm, and 7 cm, and with one angle measuring 120°, we first note that a triangle with one angle measuring more than 90° (in this case, 120°) is classified as an obtuse triangle.
Next, since all three sides of the triangle are of different lengths (3 cm, 5 cm, and 7 cm), it is a scalene triangle, as scalene triangles have no equal sides.
Combining these characteristics, we can conclude that the triangle is an obtuse scalene triangle.