Perimeter of Composite Shapes
When the Formulas Fail
On the GED® test, you may encounter shapes where the formula sheet appears to fail. Perimeter of an "ice cream cone shape"? Perimeter of an "L-shape"? Neither is on the formula sheet. In cases like this, don't panic. Remember that the perimeter can always be found by adding up all the outer sides of a shape.
STEP 1: WATCH THE VIRTUAL CLASS VIDEO AND TAKE NOTES
Make sure to note the following:
Remember that perimeter is defined as "the distance around a 2-dimensional shape". Whether you are finding the perimeter of known shapes, like a triangle, or unknown shapes, you can always total the lengths of all the sides in order to get perimeter.
To find the perimeter of composite shapes:
Make sure every side-length is labeled with a length
To find missing lengths, use the properties of the composite shape in order to find missing side lengths.
Total the side lengths
Do you have a question about the class video, practice, or example problems? Post a picture to our FB group for immediate assistance. Be sure to include the lesson name and level in your post.
STEP 2: COMPLETE ONE LEVEL OF PRACTICE
Extend your knowledge of rectangles to finding the perimeter of shapes composed of rectangles.
Find the perimeter of various compound shapes and the circumference of partial circles.