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Module 4
Angle Measure and Plane Figures


Throughout this module students will:
  • construct, recognize, and define geometric objects such as points, lines, line segments, rays, and angles
  • use a variety of strategies to create and measure angles
  • solve equations to find unknown angle measures
  • recognize lines of symmetry for two-dimensional figures
  • define and classify triangles based on angle measure and side length
  • explore definitions of familiar quadrilaterals and classify them based on their attributes, including angle measure and parallel and perpendicular  lines


Terminology Definition Illustration
Acute Angle Angle with a measure of less than 90 degrees
Acute Triangle A triangle with all interior angles measuring less than 90 degrees
Adjacent Angles Two angles with a common side and a common vertex (corner point) that do not overlap
Angle Two rays that share an endpoint
Arc Part of a circle's curve between any two of its points
Collinear Three or more points on a straight line
Complementary Angles  Two angles with a sum of 90 degrees
Degree Measure Unit for measuring angles based on dividing one circle into 360 equal parts
Diagonal Straight lines joining two opposite corners of a straight-sided shape
Equilateral Triangle Triangle with three equal sides and three equal angles
Figure Set of points in the plane
Interior of an Angle The convex region defined by the angle
Intersecting Lines Lines that contain at least one point in common
Isosceles Triangle Triangle with at least two equal sides
Length of an Arc Circular distance around the arc
Line A straight path that extends without end in both directions
Line of Symmetry A line that divides a figure into two congruent halves that are mirror images of each other
Line Segment A part of a line with two endpoints
Obtuse Angle An angle with a measure greater than 90 degrees but less than 180 degrees
Obtuse Triangle A triangle with an interior obtuse angle
Parallel  Two lines in a plane that do not intersect
Perpendicular Two intersecting lines that form right (90 degree) angles
Point Precise location on a plane
Protractor Instrument used in measuring or sketching angles
Ray Part of a line that has one endpoint and goes on forever in one direction
Right Angle Angle formed by perpendicular lines, measuring 90 degrees
Right Triangle A triangle that contains one 90 degree angle
Scalene Triangle A triangle with no sides or angles equal
Straight Angle Angle that measures 180 degrees
Supplementary Angles Two angles with a sum of 180 degrees
Triangle Consists of three non-collinear points and three line segments between them, the three segments are called sides and the three points are called vertices
Vertex A point at which two line segments, lines, or rays meet to form an angle
Vertical Angle When two lines intersect, any two non-adjacent angles formed by those lines are called vertical angles or vertically opposite angles

Module4Overview from JD K-4 Math on Vimeo.

Using a Protractor from JD K-4 Math on Vimeo.



Dr. Peter Smith, Superintendent

P.O. Box 606
DeWitt, NY 13214

Phone: (315) 445-8300

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