Warm-up 1/13/2019 Reflect the object across the y-axis. Translate the object 4 units right and 3 units up. 1. 2. Rotate the object 270 degrees counter clockwise around the origin. 3. 4. Draw a concave hexagon 5. Draw a regular pentagon 6. Draw an isosceles right triangle

Last Night’s Homework: Homework Check! Last Night’s Homework: HW1 page 399 questions 1-31, 33-39 all Today’s Objective: Chapter 7.2 page 404 “Students will know both reflections and line of symmetry.” 22.0 Students know the effect of rigid motions on figures in the coordinate plane and space, including rotations, translations, and reflections.

Today’s Objective: Chapter 7.2 page 404 “Students will know both reflections and line of symmetry.” In a reflection, a line acts like a mirror. The mirror line is called the line of reflection. Optimus Prime says… Sha-blam! Line of Reflection

Today’s Objective: Chapter 7.2 page 404 “Students will know both reflections and line of symmetry.” Bumble Bee says… While points are easy to reflect, lines can be more tricky! Here, a horizontal line is being reflected. Sha-blam! Line of Reflection

Today’s Objective: Chapter 7.2 page 404 “Students will know both reflections and line of symmetry.” Starscream says… Sloped lines are even more difficult to reflect. Here, a sloped line is being reflected! Sha-blam! Line of Reflection

Properties of Reflections Reflections in the coordinate axes have the following properties: If (x, y) is reflected in the x-axis, its image is the point (x, -y). If (x, y) is reflected in the y-axis, its image is the point (-x, y).

Today’s Objective: Chapter 7.2 page 404 “Students will know both reflections and line of symmetry.” Sha-blam! Line of Reflection

Theorem 7.1 Reflection Theorem A reflection is an isometry

Today’s Objective: Chapter 7.2 page 404 “Students will know both reflections and line of symmetry.” Jazz says… Examples: A figure in a plane has a Line of Symmetry if the figure can be mapped onto itself by a line of reflection. Non Examples:

Reflections and Line Symmetry Example: Hexagons can have different lines of symmetry depending on their shape. This hexagon has how many lines of symetry?

Reflections and Line Symmetry Given: A Regular Hexagon This hexagon has six lines of symmetry.

Checking For Understanding Sha-blam! Let’s start out easy! Reflect the following points across the line of reflection! Line of Reflection

Checking For Understanding Line of Reflection Now try to reflect this line across the line of reflection! Sha-blam!

Checking For Understanding Line of Reflection Last one! Reflect the Rectangle across the line of reflection! Sha-blam!

Checking For Understanding 3 How many lines of symmetry does each shape have? 2 2 1 5

Checking For Understanding Define: Line of Reflection Isometry Line of Symmetry Counter Clockwise Pre-image Translation Mirror line in a reflection transformation. Transformation in which pre-image and image are congruent. Line across which a figure can be mapped onto itself. To spin to the left. Starting object. To glide. Homework! HW: page 407 questions 1-29