Let’s grade homework

Pg 138 – 143; 5-9, 17-21, not 8c

3.1.3 - Proportional Equations3.1.4 – Using Proportional

equations

Ratio

A comparison of 2 things.

Can be written like:

Dogs : cats (in words)

2:1 (with a colon)

3 (as a fraction)4

An equation where 2 ratios are equal to each other

Written like:

(3 + x) = 5

7 2

Use cross products to solve.

Proportion

How are ratios and proportions the same?

How are they different?

I will number each row.

Back person: please get the appropriate paper from the back table – one paper for each person – and hand them out.

Second person from the back: please get a straightedge for everyone in your row.

Everyone: please follow the instructions on the paper and complete your paper independently.

In 5 minutes, you will be able to compare your answers to others in your row to come up with a final solution.

Then, make a table and come up with some conjectures..

• Put a point of dilation somewhere inside the shape.

• Measure the sides of your shape in cm.• Dilate the shape by a scale factor of 2.• Find the perimeter of the pre-image.• Find the perimeter of the image.• Find the area of the pre-image.• Find the area of the image.

#4

#2

#3

#1

#5

shape 1 shape 2 shape 3 shape 4 shape 5

perimeter of pre-image

perimeter of image

area of pre-image

area of image

Naming & Comparing Polygons

♥ List vertices in order, either clockwise or counterclockwise.

♥ When comparing 2 polygons, begin at corresponding vertices; name the vertices in order and; go in the same direction.

♥ By doing this you can identify corresponding parts.

A

D

C

B

E

DCBAE

P

I

J

K

H

IJKPH

D corresponds to I

AE corresponds to PH

Name corresponding parts

• Name all the angles that correspond:

A

D

C

B

E

P

I

J

K

H

D corresponds to I C corresponds to J B corresponds to K A corresponds to P E corresponds to H

DCBAE IJKPH

• Name all the segments that correspond:DC corresponds to IJCB corresponds to JKBA corresponds to KPAE corresponds to PHED corresponds to HI

How many corresponding

angles are there?

How many corresponding

sides are there?

5 5

• How many ways can you name pentagon DCBAE?

A

D

C

B

E

10

Do it.

DCBAE

CBAED

BAEDC

AEDCB

EDCBA

Pick a vertex and go clockwise Pick a vertex and go counterclockwise

DEABC

CDEAB

BCDEA

ABCDE

EABCD

Similarity Statements• Given: These polygons

are similar.

• Remember, if they are SIMILAR, corresponding sides have the same RATIO.

G

H

FE

C

D

BA

ABCD ~ EFGH

AB ~ EF

DA ~ HE

DC ~ HG

CB ~ GF

SIMILARITY STATEMENTS

SIMILARITY STATEMENT

Corresponding angles in a similar figure are congruent!!

Corresponding angles in a similar figure are congruent

A EB FD HC GC

D

BA

G

H

FE

=~

=~=~=~

Quick checkHow many different ways can you name ΔABC?

What is the relationship of corresponding sides in a similar figure?

What is the relationship of corresponding angles in a similar figure?

What happens to the perimeter of a shape that has been dilated by a scale factor of 2?

What happens to the area of a shape that has been dilated by a scale factor of 2?

What is the simplified, exact answer to: √3 + 5√3 ?

What is the name of angle pair c and h?

Are angles c and h congruent, supplementary or neither? Defend your answer.

What is the name of angle pair b and g?

What is the measurement relationship between b and g? Defend your answer.

What is the sum of the angles in a triangle?

What is the sum of the angles in a quadrilateral?

If a shape has a scale factor of 3, is the pre-image larger or smaller than the image?

a

dbh g

ec

f

Your assignment

Pg 146 – 151;

27-31, 38-42