Lesson 1

Refresher

Open "Polygon" and review the definition and naming of polygons, and explore polygons further using the demonstration applet.

To review angles in a triangle, open the “Exploring Angles Within a Triangle” interactive and answer the following questions.

1. Create a scalene triangle in which all three angles are different. What is the sum of all the angles?
2. Create an isosceles triangle in which two of the three angles are the same. What is the sum of all the angles?
3. Create an equilateral triangle in which all three angles are the same. What is the sum of all the angles?
4. What is the sum of the angles in any triangle?
   
   Recall that the triangle sum theorem states that the sum of the interior angles of any triangle is equal to 180°.
   
   
    
   
   
   

To see the importance of the Pythagorean theorem in the structural design of buildings, watch the “Exploring the Pythagorean Theorem” video.

To review the Pythagorean theorem, open the “Exploring the Pythagorean Theorem” interactive and explore the activity by changing the a and b values and see how the c value for the right-angled triangle is calculated.

Go back to the Are You Ready? section and try the questions again. If you are still having difficulty, contact your teacher.