120 likes | 268 Views
Dive into the fundamentals of angles and rays with this comprehensive guide focusing on geometric constructions and theorems. Explore how angles are formed by two non-collinear rays, learn to name angles using vertex points, and understand the classification of angles based on their measures (acute, right, obtuse, and straight). Additionally, this resource covers the methods for congruent angle constructions using various tools, including compass and straightedge. Perfect for students and educators alike, this guide emphasizes the reasoning behind geometric proofs.
E N D
1.3b: Angles & Angle constructions- Angles and Rays Common Core State Standards for Mathematical Content Congruence G-CO Prove geometric theorems [Focus on validity of underlying reasoning while using variety of ways of writing proofs] G-CO.12 Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.).; copying an angle; bisecting an angle;
Rays • A ray extends forever in one direction • Has one endpoint • The endpoint is used first when naming the ray B ray R T ray W
Angles ( ) • Angles are formed by 2 non-collinear rays • The sides of the angle are the two rays • The vertex is where the two rays meet Vertex- where the rays meet ray ray
Naming an Angle You can name an angle by specifying three points: two on the rays and one at the vertex. • The angle below may be specified as ABC or ABC. The vertex point is always given in the middle. • Named: • ABC • CBA • B * • *you can only use the • vertex if there is ONE • angle Vertex
Ex. of naming an angle • Name the vertex and sides of 4, and give all possible names for 4. T X XW & XT WXT TXW 4 Vertex: Sides: Names: 4 5 W X Z
Angles • Measured in degrees • Congruent angles – angles that have equal measures m R = m S or R S
Congruent angles: Angles that have the same measure The arc marks are used to show that the two angles are congruent
Write a statement about the congruent angles NMP RMQ Or m NMP = m RMP
Angles can be classified by their measures • Right Angles – 90 degrees • Acute Angles – less than 90 degrees • Obtuse Angles – more than 90, less than 180 • Straight Angles – 180 degrees
How to construct a congruent angle http://www.hstutorials.net/math/preAlg/php/php_09/php_09_07_x09.htm
Construct the bisector of an angle http://www.hstutorials.net/math/geometry/constructions/bisect_acute_angle.htm