8th Grade CBA-6 Review

Triangle ABC has sides measuring 15 cm, 20 cm, and 30 cm. Which could be the side lengths of the

dilated image A'B'C'?

• 9 cm, 15 cm, 18 cm

• 12 cm, 16 cm, 24 cm

• 3 cm, 4 cm, 5 cm

• 6 cm, 10 cm, 15 cm

How do we find scale factor for dilation?

•  $scale\ factor=\frac{new\ measure}{new\ measure}$  

•  $scale\ factor=\frac{new\ measure}{original\ measure}$  

•  $scale\ factor=\frac{original\ measure}{original\ measure}$  

A triangle with vertices A(-6,-3), B(3,9), and C(12,0) is dilated with the origin as the center of dilation. The vertices of new image are A'(-4,-2), B'(2,6), and C'(8,0). What is the rule of this dilation?

•  $\left(x,y\right)\rightarrow\left(\frac{5}{3}x,\ \frac{5}{3}y\right)$  

•  $\left(x,y\right)\rightarrow\left(\frac{1}{3}x,\ \frac{1}{3}y\right)$  

•  $\left(x,y\right)\rightarrow\left(\frac{2}{3}x,\ \frac{2}{3}y\right)$  

The rectangle ABCD is transformed according to the rule (x, y) --> (x-2, y -2) to create A’B’C’D’. Which statement is true?

• The side lengths of rectangle A’B’C’D’ are twice the corresponding side lengths of rectangle ABCD.

• The side lengths of rectangle A’B’C’D’ are 2 units shorter than the corresponding side lengths of rectangle ABCD.

• The angle measures of rectangle A’B’C’D’ are smaller than the corresponding angle measures of rectangle ABCD.

• Rectangle A’B’C’D’ is congruent to rectangle ABCD.

A transformation is applied to a figure to create a new figure. Which transformation does not preserve congruence?

• A translation of 10 units down.

• A dilation by a scale factor of $\frac{1}{2}$ .

• A reflection over the x-axis.

• A rotation of 90 $\degree$ about the origin.

The rectangle QPRS is translated 1 units to the down and 2 units to the right. Which rule describes the transformation that was applied to rectangle QPRS to create rectangle Q’P’R’S’?

• $(x,y)\rightarrow(x-2,y-1)$

• $(x,y)\rightarrow(x+2,y+1)$

• $(x,y)\rightarrow(x+2,y-1)$

• $(x,y)\rightarrow(x-2,y+1)$

What are the coordinates of the image of the point (x, y) after a 90 $\degree$  clockwise rotation about the origin? 

• (y, -x)

• (-y, x)

• (y, x)

• (-y, -x)

A figure is reflected across the x-axis. Which applies to the coordinates of the pre-image?

• $\left(x,y\right)\rightarrow(y,-x)$

• $\left(x,y\right)\rightarrow(x,y)$

• $\left(x,y\right)\rightarrow(-x,-y)$

• $\left(x,y\right)\rightarrow(x,-y)$

Triangle ABC was dilated to create Triangle A’B’C’. The area of Triangle ABC is 25 in² and the area of the rectangle A’B’C’ is 225 in². Which scale factor was used to dilate the rectangle?

• 3

• 2

• 1

• 5

The perimeter of a square is 36 inches. Which statement is true when the square is dilated by a scale factor of  $\frac{2}{3}$ ?

• The perimeter of the new square is 30 in

• The perimeter of the new square is 12 in

• The area of the new square is 24 in square

• The area of the new square is 36 in square