standard_description: Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so.
problem_activity: The two triangles in the picture below are congruent:
[IMG]
a.   Give a sequence of rotations, translations, and/or reflections that take
$${\triangle PRQ}$$
to
$${\triangle ABC}$$
.
b.   Is it possible to show the congruence in part (a) using only translations and rotations? Explain.


aligns: no