Download Math 8 Lesson Plan 27 Similar Polygons class outline for students

Sewanhaka High School
Math 8
Class:______________
Mrs. Lidowsky, Principal
Mr. Long, Teacher
Date:________________________
Name:__________________
H.W. #27: Ditto
DO-NOW #27: Answer the following questions:
1) Write the equation of a line that
2) Kerriann cut a piece of fabric that
passes through the points (-3, 1) and
was 7.8 meters long into 12 pieces of
(-2, -1) in point-slope form, slopeequal length. What was the length of
intercept form and standard form.
each piece?
Topic: Geometry
Main Idea: Similar Polygons
Aim:
RECALL
NOTES
Compare the triangles in picture 1. What can you
say about them? Compare the polygons in picture
2. What can you say about them?
What does it mean for 2 polygons to be similar?
What determines the shape of the 2 polygons in
picture 2 to be the same?
Refer to picture 2. List all of the corresponding
angles that are congruent.
3) David works 6.5 hours each
weekend at a bakery. What is his
hourly wage if he earns $46.80 each
weekend?
STATEMENT: Here, as in all similar figures, the ratios of the lengths of corresponding sides are equal. Because the
ratios are equal, we say that the corresponding sides are in proportion.
Two polygons are similar if their corresponding angles are congruent and their corresponding sides are in proportion.
This ratio of 2:1 is called the scale factor. It is the ratio of the lengths of the two corresponding sides of the two similar
polygons.
D
C
D'
C'
12 cm
x
A
B
16 cm
A'
8 cm
B'
Rectangle ABCD is similar to
rectangle
A'B'C'D', side AB = 16
centimeters, side AD = 12 cm,
and A'B' = 8 cm. Find the length
of AD  .
Drill: Answer the following questions. Show work.
1) Is parallelogram ABCD similar to rectangle EFGH? Prove as to why
or why not?
2) The two triangles are similar. Find the missing side measures.
SUMMARY:
If time: Answer the following question. Show work
A tree 29¾ feet tall casts a shadow 42 feet long. Mr. Short is 4¼ feet tall. How long is Mr. Short’s shadow?
Draw a diagram to represent your work.