Linear Algebra
Tuesday August 26
Homework answers
Homework Answers
Balancing a milk bottle
Answer is 3.44 miles per hour
Learning Target
Students will understand how much
information is needed to decide if two triangles
are congruent.
Connect to Prior Understanding
What do we remember about Problem 2.1
We translated ABCD 2 cm to match C with P
We rotated ABCD counterclockwise to move to
see if D matched with Q.
We found that corresponding sides and angles
were congruent.
2.2 Supporting the World
Video:
http://dashweb.pearsoncmg.com/main.html?r=
15512&p=402
Can you perform similar transformations to
show whether any two triangles are congruent?
Are any of the triangles congruent?
How do you know?
Problem 2.2 A-F
Work with a group of 3-4 students to complete
A-F.
Group Work Norms
• Work on the investigation with your group of
four
• Make sure everyone in your group participates
• Answer all questions thoroughly
• If you have a question raise your hand so that
I can can help you.
Problem 2.2
In this problem you are going to focus on congruent
triangles. Triangles are a very special family of geometric
figures. They are used in many construction projects to
provide strength and stability for structures.
You will need lab sheet 2.2 A-F
Discuss with your group how you can decide if triangles
are congruent.
What tools could you use to help you determine if figures
are congruent?
Questions
• Did you flip your tracing paper over? What
line of symmetry are you thinking of?
• After you flip your tracing over this line do you
need any other transformations?
• What did you do first in Question D?
• Were all the triangles congruent?
• How do you know they aren’t congruent?
• Do the angles in Question E match?
Share answers
• Did other groups use different order for moving their
figures?
• Did you measure angles and sides before deciding if
figures were congruent?
• How should you name the triangles to show the
corresponding congruent parts?
• How did you know that the triangles Is in Question C
are not congruent?
• How many sides do you have to measure to know that
a pair of triangles are not not congruent?
• How do you know the triangles in Question E are not
congruent?
Rate your understanding
Students will understand that two figures are
congruent if one can move one figure unto the
other by a sequence of reflections, rotations
and/or translations and will be able to show
congruence by moving a copy of the original
onto the figure.
Sorry the copy did not transfer to the PowerPoint very well! 
Answers for problem 2.2
Homework
ACE questions starting on page 38 #5-6 and
page 2 of Mathematics warm-ups for CCSS,
grade 7