1. Do Now Monday, October 23, 2017  Write on Lined Page Between S. 55-S
PART 2: Rashid drew a triangle with sides of 4 inches, 6 inches, and 12 inches. He drew a similar triangle with sides of 3 inches, 4.5 inches, and 9 inches. What scale factor did Rashid use when drawing the second triangle? Label each triangle accordingly with the measurements.
PART 1: What is the length of line segment JK if triangle ABC is similar to triangle JKL?
6 in
4 in
4.5 in
12 in
3 in ?
9 in
HINT FOR SCALE FACTOR:
Pick a corresponding side.
NEW
OLD
Is your ratio showing an enlargement or a reduction?
20 in.
3/4
The length of segment JK is ___________.
Scale Factor used: ___________________

2. What am I learning about / doing in this lesson ?
Common Core
Common Core
What am I learning about / doing in this lesson ?
How will I know that I learned the overall goal and objectives of the lesson today ?
Students use properties of similar triangles to solve real-world problems.
Students present informal arguments as to whether or not two triangles are similar.
Students practice finding lengths of corresponding sides and find missing angles when working with similar triangles.
Students know an informal proof of the Angle-Angle criterion for proving triangles to be similar and can make arguments based in the (AA) criterion.
Students can correctly identify whether two triangles are similar using information that is given or that is missing.
Students understand the relationship between corresponding sides and angles.
Students understand that similarity or congruence has criteria that must be proven, not just assumed.
Students construct viable arguments to support or disprove similarity of triangles
Can determine if insufficient information is given to prove similarity

3. Turn to page S.56 PROMPTS: What information are you given?
Do you have any corresponding sides listed?
If the two triangles are similar, do you think this picture is showing an enlargement or a reduction?
If the triangles are similar, what scale factor do you think is being used in this problem?

4. Stay on page S.56
PROMPTS:
What information is missing when comparing the two triangles?
What do you notice about AB and AB’?
What do you notice about AC and AC’?
What is different about BC and B’C’?

5. Stay on page S.56
PROMPTS:
What information is missing when comparing the two triangles?
What do you notice about AB and AB’?
What do you notice about AC and AC’?
What is different about BC and B’C’?

6. Turn to page S.57
PROMPTS:
14.8
What information are you given?
Do you have any corresponding sides or angles listed?
If the two triangles are similar, do you think this picture is showing an enlargement or a reduction?
If the triangles are similar, what scale factor do you think is being used in this problem? 8
8.5
Directions: Please modify the lengths of AB, A’B’, AC, and C’B’, using the numbers displayed in red and blue on the screen. 4

7. 5.3 10.6 AB = ___  A’B’ ___ 4.6 9.2 BC = ___  B’C’ ___
Turn to page S.58
Directions: Please modify the lengths of A’B’ and B’C’, using the numbers displayed in red on the screen.
Copy and Complete with Given information:
AB = ___  A’B’ ___
BC = ___  B’C’ ___
What other information is given?
Does this prove triangles similar?

8. Turn to page S.59
What relationship is shown that proves similarity?

9. AB = ___  A’B’ ___ BC = ___  B’C’ ___ AC = ___  A’C’ ___
Stay on page S.59
Copy and Complete with Given information:
AB = ___  A’B’ ___
BC = ___  B’C’ ___
AC = ___  A’C’ ___

10. Turn to page S.61 PROMPTS: What information are you given?
Do you have any corresponding sides or angles listed?
If the two triangles are similar, do you think this picture is showing an enlargement or a reduction?
If the triangles are similar, what scale factor do you think is being used in this problem?