10.4 Triangles10.5 Quadrilaterals

Identify and Classify Triangles and Quadrilaterals

P 428 Hands-on Mini LabFirst—Watch the demonstration

• Use a straightedge to draw a triangle with three acute angles. Label the angles A, B, and C. Cut out the triangle.

• Fold angle B so that its vertex touches the line between angles A and C. The fold should be parallel to the base of the triangle.

• Fold angle A and angle C so the vertices meet.

Questions for mini lab

• What kind of angle is formed where the three vertices meet?

• Repeat the activity with another triangle.

• Make a conjecture about the sum of the measures of three angles of any triangle.

A triangle has ___ angles.The angles add to give you ____.

1

2

3

Find x

32°

x

64°

Bermuda Triangle

P 428 example 1

p 429 example 2

An airplane has winds that are shaped like triangles. Find the

missing measure.• (In class example 1)

In class example 2

Properties of triangles video

In groups talk about the four types of triangles mentioned in

the video.

Classify by ANGLES

Acute Triangle Right Triangle Obtuse Triangle

____ angles are _______ 90°

____angles are _______ 90°

____angles are _______ 90°

Classify by Sides

Scalene Triangle Isosceles Triangle Equilateral Triangle

____ congruentsides

____ congruentsides

____ congruentsides

Classify the triangle by its angles and by its sides

Classify the triangle by its angles and by its sides

Classify the triangle by its angles and by its sides

Classify the triangle by its angles and by its sides

P 429 example 3 and 4

Workbook 10-4

Turn and Talk

• What does quad mean?

• What is a quadrilateral?

10-5 Quadrilaterals

Quadrilateral

Parallelograms Trapezoid

Rectangle Rhombus

Square

Classify the quadrilateral using the name that best describes it.

Classify the quadrilateral using the name that best describes it.

Quadrilateral Video

Classify the quadrilateral using the name that best describes it.

Classify the quadrilateral using the name that best describes it.

Angles

• Divide the parallelogram into 2 triangles.

• What is the sum of angles in both triangles?

• Then what is the sum of angles in the parallelogram?

P 435: example 3

In class example 3

More examples from workbook

Quadrant Card—Fill in the top 2 quadrants. Then exchange with a

partner and fill in the bottom 2.

Without giving it’s name, describe one type of

triangle.

Without giving it’s name, describe one type of

quadrilateral.

Draw a picture and name the triangle described above.

Draw a picture and name the quadrilateral

described above.

Homework

• p 430: 2, 5-23 and p 435: 4-6, 10-23

• DUE FRIDAY!!!