standard_description: Use the definition of congruence in terms of rigid motions to show that two triangles are congruent if and only if corresponding pairs of sides and corresponding pairs of angles are congruent.
problem_activity: Problem 1
Below is triangle
$${\triangle ABC}$$
. Rotate this shape five times clockwise about the origin.
[IMG]
Problem 2
Which one doesn't belong? Give a reason why each of the quadrants does not belong with the rest.
[IMG]
Problem 3
Suppose
$${{{ABCD}}}$$
is a quadrilateral for which there is exactly one rotation, through an angle larger than 0 degrees and less than 360 degrees, which maps to itself.  Further, no reflections map
$${{{ABCD}}}$$
to itself.
What shape is
$${{{ABCD}}}$$
?


aligns: yes