8th Grade STAAR/Benchmark Review 01(8.10ABCD, 8.3ABC, 8.5ABEFGHI

Trapezoid WKRP was translated 4 units to the left and 5 units up on a coordinate grid to create trapezoid W'K'R'P'. Which rule describes this transformation?

Answer explanation

Clue: Translations

Right = add on x

Left = Subtract on x

Up = add on y

Down = subtract on y

Tags

8.10ABCD

Triangle XYZ is rotated 90° clockwise about the origin to form triangle X'Y'Z'. Which statement is true?

• The area of triangle XYZ is equal to the area of triangle X'Y′Z'

• The area of triangle XYZ is more than the area of triangle X'Y′Z'

• The area of triangle XYZ is less than the area of triangle X'Y′Z'

Answer explanation

Clue:

(Rigid motions like translation, reflection, and rotation preserve congruency, meaning in a rotation figures would be congruent. Dilation, since it makes the figure big or small does not preserve congruency.)

Tags

8.10ABCD

A transformation is applied to a figure to create a new figure on a coordinate grid. Which transformation does NOT preserve congruence?

• A dilation by a scale factor of 1.5

• A reflection across the y-axis, or x-axis

• A translation of 125 units down

Answer explanation

Clue:

Translations, Reflections, Rotations = Preserve Congruency.

Dilation = Does not preserve Congruency.

Tags

8.10ABCD

A figure was transformed on a coordinate grid using the rule;

(x, y) → (−x, -y). Which of the following describes this transformation?

• A 180° clockwise rotation about the origin

• A reflection across the x-axis

• A reflection across the y-axis

Answer explanation

Clues: 

Reflection across x-axis (y coordinate becomes opposite)(x, y)  (x, -y)

Reflection across y-axis (x coordinate becomes opposite)(x, y)  (-x, y)

 Clockwise Rotation (SWITCH x, y) So, (x, y)  (y, -x)

 Counterclockwise Rotation (SWITCH x, y) So, (x, y)  (-y, x)

 Rotation (Both becomes Opposite) = (x, y)  (-x, -y)

Tags

8.10ABCD

Triangle ABC was transformed to create triangle A'B'C'. Which rule best describes this transformation?

Answer explanation

Clue: 

ABC became A'B'C'. It is a translation. 

Translations: Right = add on x, Left = subtract on x, Up = add on y, Down = Subtract on y.

Tags

8.10ABCD

Answer explanation

Clue: 

(Dilation multiplies the coordinates, sides and all measurements with the scale factor.)

Tags

8.10ABCD

Quadrilateral PQRS was translated 5 units to the right and 3 units up to create quadrilateral P'Q'R'S'. Which rule describes this transformation?

Answer explanation

Clue: 

Right = Add on X

Left = Subtract on X

Up = Add on Y

Down = Subtract on Y

Tags

8.10ABCD

Trapezoid PQRS is rotated 180° about the origin to form trapezoid P'Q'R'S'. Which statement is true?

• The angle measures of trapezoid PQRS are equal to the corresponding angle measures of trapezoid P'Q'R'S'. 

• The angle measures of trapezoid PQRS will NOT be equal to the corresponding angle measures of trapezoid P'Q'R'S'. 

Answer explanation

Clue:

(Translation, Reflection and Rotation preserves congruency. Congruent means corresponding sides and angles will be equal in measure.) 

Tags

8.10ABCD

Pentagon VWXYZ is shown on the coordinate grid. A student reflected pentagon VWXYZ across the x-axis to create pentagon V'W'X'Y'Z'. Which rule describes this transformation?

Answer explanation

Clue: 

Reflection across x-axis = Y coordinates become opposite. 

Reflection across y-axis = X coordinates become opposite.

Tags

8.10ABCD

Triangle RST is translated 6 units to the left and 4 units up to create triangle R'S′T′. Which rule best describes this transformation?

Answer explanation

Clue: 

Translations: Right = add on X, Left = Subtract on X, Up = Add on Y, Down = Subtract on Y

Tags

8.10ABCD