Shape 

Copyright David & Cynthia Thomas, 2009

 

Area--Directed Activity: Triangles & Trapezoids

 

The directed activities in this section provide a context in which to investigate how area is represented and computed in coordinate geometry relative to …

·        Triangles

·        Polygons

                                                           

Focus

Triangles and trapezoids

Technologies

The Geometers Sketchpad and the model 5_TriTrap.gsp 

Background

Figure 5.14: Triangle Area

Tasks

·        Find the areas of the three trapezoids: ACDE, AEFB, and CDFB. 

·        Find the area of ΔABC.

·        Express the area of ΔABC in terms of the areas of the three trapezoids.

·        Check your findings using The Geometers Sketchpad and the model 5_TriTrap.gsp