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3.B: Polygons - Angles, Area and Perimeter

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    The purpose of this lesson is to learn how to find the area and perimeter of various polygons and to identify the angle sum of any polygon.

    This lesson will address the following CCRS Standard(s) for Geometry:

    • 7.G.6: Solve real-world and mathematical problems involving area, volume and surface area of two- and three- dimensional objects composed of triangles, quadrilaterals, polygons, cubes, and right prisms
    • G.MG.2: Apply concepts of density based on area and volume in modeling situations (e.g. persons per square mile, BTUs per cubic foot)


    1. Take notes while watching videos below
    2. Go to and log into our course to complete assignment 3.B with 80% or better.


    Complete assignment 3.B with 80% or better at


    In this lesson we have learned:

    • Perimeter of any polygon is the sum of the sides
    • Area of a triangle: LaTeX: A=\frac{1}{2}bh
    • Area of a parallelogram: LaTeX: A=bh
    • Area of a trapezoid: LaTeX: A=\frac{1}{2}h\left(b_1+b_2\right)
    • Area of a regular polygon is: LaTeX: A=\frac{1}{2}Pa
    • The angle sum of any polygon is: LaTeX: 180\left(n-2\right)</mo> <mn>2</mn> </mrow> <mo>)</mo> </mrow> </math>' data-equation-content="180\left(n-2\right)">

    3.B: Polygons - Angles, Area and Perimeter is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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