Reflection Symmetry
The line that divides a shape into two mirror-image halves.
What is the reflection line.
A shape has _________________ if it can be rotated less than 360 degrees about its center and still look the same.
What is rotational symmetry?
What makes a polygon “regular”?
All sides equal and all interior angles equal.
Name the three basic transformations that preserve size and shape.
Translation, rotation, reflection
What does “congruent” mean for two polygons?
Same shape and same size
This shape has infinite symmetry.
What is a circle?
The order of rotation when a shape matches itself after being rotated 180 degrees.
What is an order of rotation of 2?
Is a rectangle a regular polygon? Explain why or why not.
No. A rectangle has equal opposite sides and equal angles but not all four sides equal (unless it is a square).
If a figure is translated right 3 units and up 2 units, how does a point move? (Give new coordinates.)
New point: (4,1) because (1+3 = 4) and (-1 + 2 = 1).
If two triangles have the same side lengths in the same order, are they congruent?
Yes
This shape has only one line of symmetry.
Isosceles triangle
The letter N (uppercase) generally has rotational symmetry of this order.
What is 2
List two differences between a regular pentagon and an irregular pentagon.
Regular pentagon: all sides and angles equal; irregular pentagon: sides and/or angles differ. Symmetry: regular pentagon has reflection/rotational symmetries; irregular generally does not.
Describe the difference between a reflection and a rotation.
Reflection flips a figure across a line producing a mirror image; rotation turns a figure around a point by an angle
When a shape is reflected over the x-axis, this coordinate remains the same.
What is the x-coordinate.
True or False. A kite-shaped quadrilateral has at least one line of symmetry.
True
A shape has rotational symmetry of order 4. What are all the angles (in degrees) less than that will map the shape onto itself?
90
Give an example (name or sketch) of an irregular polygon with five sides where none of the sides are equal.
Any 5-sided polygon with sides of different lengths, e.g., vertices placed randomly without equal-length constraints.
A triangle is rotated clockwise about the origin. Point is at . What are the coordinates of the image of after the rotation?
For a 90 degree rotation about the origin, (x, y) --> (y, -x) so (2,1) --> (1,-2)
Describe how two shapes can be congruent without being related by reflection or rotation symmetry.
Two shapes can be congruent without being related only by reflection or rotation because they can be related solely by a translation (sliding). A translation moves a shape from one location to another without changing its orientation