Today while looking through the app store, I discovered a nice little app, Geometry Pro, that can be used in both Algebra I and Geometry. It is nice as it covers two and three dimensional shapes and solid to points and line, circles, polygons, and proofs.
Each topic has information, video's, calculators depending on the topic selected. I see this as a quick reference for students as they are working through each topic. This way, they do not have to search the textbook to find the exact material they want. It is there in a nice encapsulated form.
The regular polygon section includes finding information if you are given the radius, the side or the apothem. Each of these subsections has a illustration, a small calculator, and the information for finding various formulas with explanations. For instance, if I use the attribute finder for a given side for an 8 sided figure that has sides of 4 units, I get the following information.
Angle x (1/2 of the central angle) = 22.5 degrees
Angle y (interior angle) = 135 degrees
Angle z (exterior angle) = 45 degrees
radius = 5.226
apothem = 4.828
Perimeter = 32
Area = 77.255
I like the way this is set up and I can have students use it to reinforce their learning and check their work. This polygon calculator can be used for anything beginning with triangles and going to n-gons.
I like that it can be used for parallel lines, slope, midpoint, distance and two lines or systems of linear equations for Algebra I, review for Algebra II and parts of Geometry. The best thing of all, its free!