True or false and reason: 1.   an angle changes in size as it undergoes a dilation. 2. a line segment usually decreases in size under contraction. 3. there can only be one obtuse angle in a triangle. 4. if a figure is reflected across the x-axis it is congruent to the original figure. 5. a figure derived from a previous figure by rotation, translation or dilation will be congruent to the original figure.

1.  An angle changes in size as it undergoes a dilation.
FALSE because an angle or triangle will stretch the lengths of sides while maintaining the same angular degrees

2. A line segment usually decreases in size under contraction.
TRUE because contraction is shortening (opposite of dilation)

3. There can only be one obtuse angle in a triangle.
TRUE because 180 Rule: if one is greater than 90, then other 2 have to sum (and therefore be less than) 90

4. If a figure is reflected across the x-axis it is congruent to the original figure.
TRUE, reflection does not change dimensional aspects, only mirrors the figure across x or y axis

5. A figure derived from a previous figure by rotation, translation or dilation will be congruent to the original figure.
FALSE, only because dilation (stretching) changes the dimensional aspects