Reflection
Yes
No
Reflection
Yes
No
Line Symmetry
A figure has line symmetry if a line can be drawn on a it which creates
two sides that are reflections of one another
The red line (line of symmetry) creates two triangles which are reflections of one another. Therefore, this triangle has line symmetry
Do these figures have line symmetry? If so, draw the lines
YESYES
NO
Do these figures have line symmetry? If so, draw the lines YES
NO
Do these figures have line symmetry? If so, draw the lines
YES
YES
Point out objects in this room that have line symmetry
Draw 1 figure that has 1 line of symmetry
Draw one figure that has more than 1 line of symmetry
Line of ReflectionWhen you reflect a figure in a line, the line is
called the line of reflection
KEY CONCEPTTo reflect a point in the x-axis, multiply its y-coordinate by -1Ex: (x,y) turns into (x,-y)Ex: (2,3) turns into (2, -3)
To reflect a point in the y-axis, multiply its x-coordinate by -1Ex: (x,y) turns into (-x,y)Ex: (2,3) turns into -2,3)
Examples using Y axisOriginal Points:1,31,13,13,3
Reflected Points:-1,3-1,1-3,1-3,3
Multiply all the X Coordinates with -1
Examples using X axisOriginal Points:1,31,13,13,3
Reflected Points:1,-31,-13,-13,-3
Multiply all the Y Coordinates with -1
REFLECT THIS IMAGE ON THE X AXIS
POINTS:-1,4-1,1-4,4
REFLECT THIS IMAGE ON THE X AXIS
POINTS:-1,4-1,1-4,4
Reflected Points-1,-4-1,-1-4,-4
REFLECT THIS IMAGE ON THE Y AXIS
POINTS:-1,4-1,1-4,4
REFLECT THIS IMAGE ON THE Y AXIS
POINTS:-1,4-1,1-4,4
Reflected Points1,41,14,4
GRAPH THESE POINTS THEN REFLECT THEM ON THE X AXIS
1,-14,-11,-34,-3
Correctly Graphed
Correctly Graphed
Reflected Points:1,14,11,34,1
Homework
PAGE 434Guided Practice #3
PAGE 435Skill Practice # 6,7,8