Physics 122 Collisions in 2D!  Do the example problem in your notes. Physics 112 Practicing the Lens Equation (Worksheet #1 - 13, not #8) Astronomy 120 Chapter 10 on the Sun. #1 - 19 at the end of Chapter 10. Math 9 Triangle angle properties for similarity (angle_properties_for_similar_triangles.pdf). Writing the similarity statement and side ratios (similarity_statement_-_practice.pdf). Do #s 1 - 4 on the second page of the similarity statement practice worksheet (above).