Activity 4: Dilatations

What is a dilatation in geometric transformations?

• A dilatation is a reflection in geometric transformations.

• A dilatation is a translation in geometric transformations.

• A dilatation in geometric transformations is a transformation that enlarges or reduces the size of a figure without changing its shape.

• A dilatation is a rotation in geometric transformations.

Tags

CCSS.8.G.A.3

How do you calculate the scale factor of a dilatation?

• Scale factor = Length of pre-image / Length of image

• Scale factor = Perimeter of image / Perimeter of pre-image

• Scale factor = Area of image / Area of pre-image

• Scale factor = Length of image / Length of pre-image

Tags

CCSS.7.G.A.1

If a point has coordinates (2,3) and is dilated by a scale factor of 2 with centre (0, 0), what are the coordinates of the image point?

• (1, 2)

• (4, 6)

• (5, 8)

• (3, 5)

Tags

CCSS.8.G.A.3

If a figure is dilated with a scale factor greater than 1, how does the size of the image compare to the original figure?

• It is larger

• It is smaller

• It is the same size

• It depends on the figure

Tags

CCSS.8.G.A.3

  Which transformation is described by the mapping notation (x, y) → (2x, 2y)?

• Translation

• Reflection

• Rotation

• Dilatation

Tags

CCSS.8.G.A.3

The size of a figure changes in a ___________________________.

• Translation

• Reflection

• Rotation

• Dilatation

Tags

CCSS.8.G.A.3

What is the mapping notation used for a dilatation?

• (x, y) -> (kx, y)

• (x, y) -> (x + k, y + k)

• (x, y) -> (kx, ky)

• (x, y) -> (x - k, y - k)

Tags

CCSS.8.G.A.3

If a figure is dilated by a scale factor of 0.5, what happens to its size?

• The size of the figure is reduced by half.

• The size of the figure remains the same.

• The size of the figure is doubled.

• The size of the figure is increased by half.

Tags

CCSS.8.G.A.3

If a point P is dilated by a scale factor of 4 with center at the origin, what are the coordinates of the image point if the original coordinates of P are (3,6)?

• (12, 24)

• (6, 12)

• (9, 18)

• (15, 30)

Tags

CCSS.8.G.A.3

The point X (2, -7) is dilated to its image X’(4, -14) with dilatation centred at the origin. What is its scale factor?  

• 1

• 2

• 3

• 4

Tags

CCSS.8.G.A.3