Question

2. Draw the image of RST under the dilation with scale factor 2/3 and center of dilation (1,-1). Label the image RST .

Answer 1

Answer:

From the graph: we have the coordinates of RST i.e,

R = (2,1) , S = (2,-2) , T = (-1,-2)

Also, it is given the scale factor $\frac{2}{3}$ and center of dilation C (1,-1)

The mapping rule for the center of dilation applied for the triangle as shown below:

$(x, y) \rightarrow (\frac{2}{3}(x-1)+1, \frac{2}{3}(y+1)-1)$

or

$(x, y) \rightarrow (\frac{2}{3}x -\frac{2}{3}+1 , \frac{2}{3}y+\frac{2}{3}-1)$

or

$(x, y) \rightarrow (\frac{2}{3}x+\frac{1}{3} , \frac{2}{3}y-\frac{1}{3} )$

Now,  

for R = (2,1)  

the image R' = $(\frac{2}{3}(2)+\frac{1}{3} , \frac{2}{3}(1)-\frac{1}{3} )$ or

$(\frac{4}{3}+\frac{1}{3} , \frac{2}{3}-\frac{1}{3} )$

⇒ R' = $(\frac{5}{3} , \frac{1}{3})$  

For S = (2, -2) ,

the image S'=  $(\frac{2}{3}(2)+\frac{1}{3} , \frac{2}{3}(-2)-\frac{1}{3} )$ or

$(\frac{4}{3}+\frac{1}{3} , \frac{-4}{3}-\frac{1}{3} )$

⇒ S' = $(\frac{5}{3} , -\frac{5}{3})$

and For T = (-1, -2)

The image T' =  $(\frac{2}{3}(-1)+\frac{1}{3} , \frac{2}{3}(-2)-\frac{1}{3} )$ or

$(\frac{-2}{3}+\frac{1}{3} , \frac{-4}{3}-\frac{1}{3} )$

⇒ T' = $(\frac{-1}{3} , \frac{-5}{3})$

Now, label the image of RST on the graph as shown below in the attachment: