Length, Perimeter and Area

How do 2-D properties relate in 3-D? Lead the class in a discussion on how to draw and see relationships of lines and planes in three dimensions. The ability to see these relationships is critical to the further study of volume and...

Sal uses the elimination method to simplify a system of three variables. Next, he employs the substitution method to check his solution. This resource would nicely complement any lesson on this topic.

Slice up solids. A portion of a geometry playlist introduces two conventional ways to visualize 3-D figures in 2-D. The resource defines cross-sections and nets and provides examples of both.

Lateral area and surface area are simple concepts, but calculating them is not as easy! Using formulas, learners calculate lateral area and surface area for the same three-dimensional figures. The resource discusses the formula variables...

Learn the mathematics behind modeling in three dimensions to maximize or minimize one aspect of the situation.

In order to better understand why your world is three dimensional, consider zero, one and two dimensions.

Cross-sections are one way that two-dimensional objects are connected to three-dimensional objects.

Explore connections between a 2-dimensional net and a 3-dimensional box. Later in this section, use equations with variables to solve real world problems that use 2 and 3-dimensional objects.

Use the formula for the perimeter of a rectangle to find the value of the width. Plug the given values of the perimeter and the length into the formula and solve. It is as easy as it looks.

The teacher illustrates a diagram to help you learn about perimeter. First she adds the sides together to get the perimeter. Then she shows how to use the perimeter formula to make it a bit simpler.