1-4 Angle Measure.ppt
- 1. SEC 1-4 JIM SMITH JCHS
- 2. A ray is part of a line. It has 1 endpoint and goes on forever in one direction. When naming a ray, we use the endpoint first and a “ go through “ point last. Ray AB or AB starts at point A and goes through point B A B C We could also name this ray AC BA starts at B and goes through A RAYS We do not flip the symbol
- 3. Opposite rays have the same endpoints but travel in opposite directions along the line. Y Z X YX and YZ are opposite rays • Opposite Rays Opposite rays form a line
- 4. Angles are formed by 2 rays that have a common endpoint. The rays are called the sides and the common endpoint is called the vertex. Angles A B C X Y Z SIDE BA SIDE BC SIDE YX SIDE YZ VERTEX VERTEX • •
- 5. Naming Angles Angles can be named 3 ways. You can connect the dots using 3 points. Use 1 point from each side with the vertex in the middle. A C B ‹ ABC or ‹ CBA You can use just the vertex if it is the only angle with that vertex. ‹ B You can use a number if one is given. ‹ 1 1
- 6. Classifying Angles Angles can be classified by their measure. A circle is divided into 360 degrees. An angle measurement is going to be part of the circle. 63°
- 7. Right angles Acute angles Obtuse angles Straight angles = 90° < 90° > 90° = 180° •
- 8. Protractors are used to measure angles. Align the vertex of the angle with the hole in the protractor. Align one side of the angle with the zero on either side of the protractor. Read the smaller numbers from the first side to the second side. 65°
- 9. 76°
- 10. Actually, if you align the vertex you only have to find the absolute value of the difference of the numbers │70° - 140°│ = 70° │40° - 110°│ = 70°
- 11. Angle Bisector A ray that divides an angle into 2 congruent parts is called an angle bisector. 1 2 m‹ 1 = m‹ 2
- 12. A B C D E G H I M F • Name the vertex 1. ‹ 1 2. ‹ 4 3. ‹ 6 4. ‹ 7 Name the sides 1. ‹ AIE 2. ‹ 4 3. ‹6 4. ‹AHF Give another name 1. ‹ 3 2. ‹ DEF 3. ‹ 2 4. ‹ 5 5. ‹ 4 1 2 3 4 5 6 7 B E G I IA & IE ED & EF GC & GH HA & HF ‹ GCD ‹ 4 ‹ BCG ‹ DEM ‹ FED