      Module 4
Angle Measure and Plane Figures

Overview

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

Vocabulary

 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 DISTRICT

OUR SCHOOLS  Dr. Peter Smith, Superintendent P.O. Box 606 DeWitt, NY 13214 Phone: (315) 445-8300 www.jamesvilledewitt.org

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