BELL WORK

Open your books to Stretching & Shrinking, Page 38

Have a piece of paper and pencil ready for notes.

Find the perimeter and area of the two figures below.

3

3

4

1Perimeter = 12

Area = 9

Perimeter = 10

Area = 4

SECTION 3.1SIMILAR FIGURES

Similar Polygons

Similar Polygons

Similar Polygons

Similar Polygons

Similar Polygons

IMPORTANT VOCABULARY

Rep-tile – A figure you can use to make a larger, similar version of the original.

Unit 3.1 Rep-tile Quadrilaterals In the pencil box on your desk you will

find plastic bags with the following shapes.

A non-square rectangle A non-rectangular parallelogram A trapezoid

Each team member will need four of each shape.

Are They Rep-tiles?

A. Which of these shapes can fit together to make a larger shape that is similar to the original?

Make a sketch to show how the copies fit together.

All three shapes are rep-tiles.

Use Your Sketches from Question A

1. What is the scale factor from the original figure to the larger figure?

2. How does the perimeter of the new figure compare to the original?

The scale factor is 2. The lengths of the new shape are two times as long as the original.

The perimeter doubles because each side is twice as long as the original. The perimeter goes up by the scale factor.

Use Your Sketches from Question A

1. How does the area of the new figure compare to the original?The area is four times as large.

Four of the original shape can fit in the new figure.

The area goes up by the scale factor squared.

Work as a Team

Scale Factor: 3

Perimeter: 3x bigger

Area: 9x bigger

Scale Factor: 4

Perimeter: 4x biggerArea: 16x bigger

Sides: 3x longer Sides: 4x bigger

ACE Questions, Page 50, #22

Supplementary Angles – Two angles that form a straight line. The sum of the angles is 180 degrees.

ACE Questions, Page 50, #22

Which angles above are supplementary?a and b a and c b and 120d and e d and g e and f

ACE Questions, Page 50, #22

What are the measures of the missing angles?a = 120 d = 120 g = 60

b = 60 e = 60c = 60 f = 120

ACE Questions, Page 50, #24

50 degrees

Find the measure of angle R. Explain how you can find the measure of angle C.

ACE Questions, Page 50, #24

Find the measure of angle R and Q.

40

50

Angle R = 50 degrees

Angle Q = 40 degrees

EXIT SLIP

Answer the following in complete thought sentences.

What happens to the side lengths, perimeter and area of shape that is enlarged by a scale factor of 2?

Use at least two complete sentences.