FINDING THE AREA OF A TRAPEZOID
Instructions
Introduction and Background
You can find the area of many polygons even if you can’t remember the appropriate formula. Deconstructing the polygons into smaller, simpler polygons with which you are more familiar can provide a tool for finding area. Once you know…
to use these three polygons to construct a new trapezoid. If you need to rotate a triangle, click on the Show/Hide Rotator Points option.
Step 2. Find the Areas of the Pieces
Turn on the GRID to use as a measuring tool.
Complete the following calculations:
Red Rectangle: area= base X height
area= ________units X ________ units = ________ sq. units
Green Triangle: area= ½ X base X height
area= ½ X ________units X ________ units = ________ sq. units
Blue Triangle: area= ½ X base X height
area= ½ X ________units X ________ units = ________ sq. units
Area of Trapezoid=
______ sq. units + ______sq. units + ______ sq. units = ______ sq. units
Step 3. Check your Calculations
Click on the Show/Hide Rotator Points option to hide the rotator points. Use the AREA tool 
to label each of the three polygons with their areas. Use this to check your work.
- that the area of a rectangle can be found by using the formula: area of a rectangle = base X height
- and that the area of a triangle (since it is half of a rectangle) can be found by using the formula: area of a triangle = ½ X base X height you can deconstruct other, more complex polygons, into rectangles and triangles and find their area in square units.
to use these three polygons to construct a new trapezoid. If you need to rotate a triangle, click on the Show/Hide Rotator Points option.
Step 2. Find the Areas of the Pieces
Turn on the GRID to use as a measuring tool.
Complete the following calculations:
Red Rectangle: area= base X height
area= ________units X ________ units = ________ sq. units
Green Triangle: area= ½ X base X height
area= ½ X ________units X ________ units = ________ sq. units
Blue Triangle: area= ½ X base X height
area= ½ X ________units X ________ units = ________ sq. units
Area of Trapezoid=
______ sq. units + ______sq. units + ______ sq. units = ______ sq. units
Step 3. Check your Calculations
Click on the Show/Hide Rotator Points option to hide the rotator points. Use the AREA tool to label each of the three polygons with their areas. Use this to check your work.