Rotational Symmetry and Angles

The video tutorial explains rotational symmetry, where an object maps onto itself after a rotation of 180 degrees or less. It covers examples using squares, rectangles, equilateral triangles, pentagons, trapezoids, circles, and windmill shapes. The tutorial demonstrates how to calculate angles of rotation for regular polygons and highlights the unique infinite symmetry of circles.

What is rotational symmetry?

• When an object can be shrunk and still looks the same.

• When an object can be rotated and still looks the same.

• When an object can be flipped and still looks the same.

• When an object can be stretched and still looks the same.

What is the maximum degree of rotation for an object to have rotational symmetry?

• 360 degrees

• 270 degrees

• 180 degrees

• 90 degrees

How many degrees must a square be rotated to map onto itself?

• 120 degrees

• 60 degrees

• 45 degrees

• 90 degrees

What defines a regular polygon?

• All sides and angles are different.

• All sides and angles are the same.

• All sides are the same but angles are different.

• All angles are the same but sides are different.

How do you calculate the angle of rotation for a regular polygon?

• 180 divided by the number of angles

• 360 divided by the number of angles

• 180 divided by the number of sides

• 360 divided by the number of sides

What is the angle of rotation for a rectangle?

• 180 degrees

• 120 degrees

• 90 degrees

• 360 degrees

What is the angle of rotation for an equilateral triangle?

• 120 degrees

• 90 degrees

• 180 degrees

• 60 degrees

How many degrees must a pentagon be rotated to map onto itself?

• 90 degrees

• 54 degrees

• 36 degrees

• 72 degrees

Why does a trapezoid not have rotational symmetry?

• It can only map onto itself at 360 degrees.

• It can map onto itself at 180 degrees.

• It can map onto itself at 90 degrees.

• It can map onto itself at 45 degrees.

What is unique about the rotational symmetry of a circle?

• It has finite rotational symmetry.

• It has rotational symmetry only at 180 degrees.

• It has no rotational symmetry.

• It has infinite rotational symmetry.