We just used 90 degree rotations, but what
if we decided to do a 180 degree, or 270 degree rotation of triangle
ABC?
Find the rotation matrix for a 180 degree rotation.
There are two different ways to approach this problem. Try
each approach and compare your answers.
a) Using the original coordinates of ABC, what are the
coordinates of A"B"C" when ABC is rotated 180 degrees about the
origin? Use your knowledge of inverse matricies to find the
rotation matrix.
b) What is the relationship between a 90 degree rotation and
a 180 degree rotation? If you are only allowed to use 90 degree
rotations, how would you rotate ABC 180 degrees about the origin?
Use this method to find the origin.
c) Using your knowledge from what we
did in class today, and the previous two questions, how would you
rotate ABC 270 degrees about the origin? Show using an example,
and write a paragraph explaining your answer. You may use any
method you wish, but be sure to justify your conclusions. This
should be neatly written or typed and ready to hand in tomorrow.