Happy Monday 
1. Take out your stamp sheet and the worksheet you did
on Friday
2. Write down the homework on your stamp sheet.
3. Have your homework packet ready before the bell
rings
– This means stapled.
Tonight’s Homework
• P 465 # 1-6, 11, 13-18
- Start your Similar Figures Project- due Wednesday
Agenda
Homework quiz
3 Things
Go over worksheet from Friday
Turn in homework packet
7.2: Ratios in Similar Polygons
Go over projects
Homework quiz
Answer the following question on the back of
your stamp sheet.
What was the answer to #13 on page 457.
Show all your work
3 Things
Whiteboard
1. If ∆QRS  ∆ZYX, identify the pairs of
congruent angles and the pairs of congruent
sides.
2. Solve the proportion
7.2: Ratios in Similar Polygons
Learning Objective
(1 ) SWBAT identify similar polygons
(2) SWBAT apply properties of similar
polygons to solve problems
Work With A Partner…
Ms. Huls wants to build a new math room at Leland, but first
she wants to see a scale model of the room.
• The scale model is 1/3 the size of the real room.
• The actual classroom door is 6 ft. tall.
• The model’s door is 1 ft. wide.
1.
2.
3.
4.
Set up a proportion involving the dimensions of the door.
How tall is the door in the model?
How wide is the actual door?
What is the ratio of the area of the model’s door to the
area of the real door?
Figures that are similar (~) have the same shape but not
necessarily the same size.
Similar Polygons
Two polygons are similar
polygons if and only if
their corresponding
angles are congruent and
their corresponding side
lengths are proportional.
Example 1: Describing Similar
Polygons
Identify the pairs of congruent angles and
corresponding sides.
0.5
Whiteboard
Identify the pairs of congruent angles and
corresponding sides.
Vocabulary
Similarity ratio ( or scale factor)
• ratio of the lengths of the corresponding sides
of two similar polygons
• how much the figure is enlarged or reduced
– Dilation
Example 2: Identifying Similar Polygons
Determine whether the polygons are similar. If
so, write the similarity ratio and a similarity
statement.
Whiteboard
Determine whether the polygons are similar. If
so, write the similarity ratio and a similarity
statement.
∆ABCD and ∆EFGH
Car Models
Find the length of the model to the nearest
tenth of a centimeter.
Whiteboards
A boxcar has the dimensions shown. A model
of the boxcar is 1.25 in. wide. Find the length of
the model to the nearest inch.
Closure
Determine whether the polygons are
similar. If so, write the similarity ratio
and a similarity statement. If not,
state why.
Closure
2. The ratio of a model sailboat’s
dimensions to the actual boat’s
dimensions is
. If the length of
the model is 10 inches, what is the
length of the actual sailboat in feet?
Closure
Tell whether the following statement is
sometimes, always, or never true and
state why.
Two equilateral triangles are similar.
Download

Determine whether the polygons are similar. If so, write