Def : Rays Geometry Lesson: Rays, Angles A ray is a part of a line that consists of an endpoint, and all points on one side of the endpoint. Def: Opposite Rays Opposite Rays are two rays of the same line with a common endpoint and no other points in common. P A A B P
A line segment has a starting point and an ending point. Line segments can be measured.
A line segment also defined by 2 points. E F Line Segment EF
Def :Angle: Geometry Lesson: Rays, Angles An angle is the union of two rays having the same endpoint. Three capital letters, with vertex in the middle : Single lowercase letter or number inside the angle: Use the name of the vertex angle if it’s the only angle at that vertex: side side vertex B A C x Naming Angles: a) b) c)
When lines intersect to form right angles, they are said to be perpendicular. V R T U c S UT RV
These angles can be right angles. c R S T U V RST = 90 ⁰ USR = 90 ⁰ USV = 90 ⁰ TSV = 90 ⁰
Lines can also run into each other to form straight angles.
Def: Straight Angle Geometry Lesson: Rays, Angles A straight angle is the union of two opposite rays. A B O Straight angles have a measure of 180 ° Def : Righ t Angle: M Q P A right angle has a measure of 90 °
Lines can intersect to form acute and obtuse angles. 135 obtuse 45 acute
Def: Acute Angle: Geometry Lesson: Rays, Angles Y X Z An acute angle has a measure greater than 0 ° and less than 90 °. Def: Obtuse Angle: Q X R An obtuse angle has a measure greater than 90 ° and less than 180°.
Angle Measure: Geometry Lesson: Rays, Angles Def: Congruent Angles B A C 25 ° are angles having equal measure. Ans. The measure of an angle is the number of degrees in the angle. Q: Which of the following angles are congruent? A) 45 ° A C) C 45 ° B) B 45 °
Def: Perpendicular Lines Geometry Lesson: Rays, Angles are two lines that intersect to form right angles . Right Angles: Straight Angle: Are lines m and l perpendicular? NOT UNLESS SPECIFIED BY THE GIVEN INFO OR A BOX IN THE DIAGRAM !!!! l m H K L J