Lesson 1

Discover

 

Suppose you are a skilled carpenter, and you have been asked to construct a gazebo similar to the one shown. As you can see, there are a number of different shapes involved in the design of this structure, in particular, triangles. How will you determine the lengths and angles of each piece that needs to be cut, such that the pieces fit nicely together?

 

Complete the following Try This activity to develop your understanding of different types of triangles.

 

Try This 1

 

Open the Triangle Demonstration Applet and analyze the constructed triangle after following the instructions. Record your findings after each set of instructions.

 

1. Click and drag the top corner of the triangle until all the angles are equal and the side lengths are equal. Look above the triangle. What kind of triangle is this?
2. Now click and drag the top corner of the triangle to the side of the screen. Look above the triangle. What kind of triangle is this?
3. Now click and drag the top corner of the triangle to make one angle in the triangle a right angle (90°). Look above the triangle. What kind of triangle is this?

Save your responses in your course folder.

 

Share 1

 

With a partner or in a group, share your responses to Try This 1 and address the following additional questions:

1. What characteristics classify a triangle as right, scalene, isosceles, or equilateral?
2. What characteristics classify a triangle as acute or obtuse?
3. Can a triangle be classified by its sides as well as its angles? Explain, and provide examples if possible.
4. Is it possible to change the length of one side of the triangle without affecting other parts of the triangles (sides and angles)?

If required, place a summary of your discussion in your course folder.