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. Set up a proportion involving the dimensions of the door.

2. How tall is the door in the model?

3. How wide is the actual door?

4. 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.

Two polygons are similar polygons if and only if their corresponding angles are congruent and their corresponding side lengths are proportional.

Similar Polygons

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.