Section 5.2: Polygons and Angles
Essential Ideas

  • The Essential Idea for this section is the introduction of new terminology. The terms that you need to pay attention to are those boldface terms in this section: polygon, triangle, quadrilateral, pentagon, hexagon, heptagon, octagon, nonagon, decagon, dodecagon, n-gon, vertex, angle, equal angles, degree, and protractor. See if you can find each of these terms in this section.

  • You should be able to classify angles as follows:
    Acute angle    less than 90 degrees
    Right angle    equal to 90 degrees
    Obtuse     between 90 degrees and 180 degrees
    Straight    equal to 180 degrees

  • In this section one additional construction is considered, namely constructing an angle congruent to a given angle.