## IGD: Area of a Rectangle

3-5, 6-8
Standards:
Math Content:
Geometry

How Do You Find the Area of a Rectangle?

To measure the length of a segment, you use a unit length such as an inch, a centimeter, or a foot, and you see how many times it goes into the segment you are measuring. To measure an area, you use a square unit, such as a square inch, a square centimeter, or a square foot, and see how many times it goes into the area you are measuring.

• Drag point B or D to change the dimensions of the rectangle.
• Point A will not move, and point C will adjust automatically as the dimensions of the rectangle change.
A square unit is the basic unit of measurement of area. To measure an area, find out how many of these go into it.

The unit square fits into the rectangle shown here 15 times, so its area is 15. How can you find the area of any rectangle? In the applet below, the dimensions and area of a rectangle are given. How do you use the dimensions to find the area?

Area of a Rectangle = Base × Height

Use what you know about the area of a rectangle to find the Area of a Parallelogram.

### IGD: Area of a Parallelogram

3-5, 6-8
This applet will show you how to divide the parallelogram into pieces, arrange them together to form a rectangle, and then use the formula for the area of a rectangle to find the area of the parallelogram.

### IGD: Area of a Triangle

3-5, 6-8
Use this tool to prove how to find the area of a triangle.