Geometry (G)

Perimeter

  • What is Perimeter: The outside of a 2D shape. 

    How to find perimeter: ADD up ALL sides of a shape.

    Note: If there are no numbers located on a side, you have to decide based on the numbers given what the measument of the unknown is. 

     

    Video: Perimeter: Khan Academy

     

    Helpful IXL: FF.1


Area

  • What is Area: The inside of a 2D shape. 

    Area of a Rectangle: 

    Area = Base x Height

    Example: 

    Area of a Rectangle  

    Base = 8cm

    Height = 5cm

    A = 8cm x 5cm

    A = 40 cm²

     

    ** Helpful IXL FF.2

     

    Area of a Parallelogram

    Area = Base x Height

    Paralellograms have the same formula as a rectangle because parallelograms are made from rectanges. (See you notes for an example)

    Area of a Parlellogram

    Base = 10in

    Height = 5in

    A = 10in x 5in

    A = 50 in²

     

    **Helpful IXL FF.4

     

    Area of a Triangle

    Area = Base x Height ÷ 2

    Note: You must ALWAYS divide this by two because it is half of a rectangle. (See your notes for an example)

    Area of a Triangle

    (you only use 5 and 9 for the perimeter, it is not needed for the area)

    Base= 12 units

    Height = 4 units

    A = 12 x 4 ÷ 2

    A = 48 ÷ 2

    A = 24 units²

     

    ** Helpful IXL: FF.3

     

    Area of a Trapezoid

    Note: In order to find the area of a trapezoid you must decompose the shape into TWO triangles. Once you find the area of both triangles you will then add the two triangles together to get the total area of the shape. 

    Area = Base x Height ÷ 2

     

    Trapezoid 1 Trapezoid 2

    Trapezoid Work

     

    Total Area = 3 in² + 6 in² = 9 in² 


Surface Area

  • What is Surface Area: The area of all sides of a 3D shape. 

    How do you find Surface Area: By finding the area of all shapes and then adding them together. 

     

     

    Net: is a flattened 3D shape.

     

    3D and Net

    Finding the Surface are of a Net:

    Find the area of each individual shapes using the correct formula and then add them all together. 

    Rectangular Prism:

    Rectangular Prism

    Triangular Prism

    Triangular Prism