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24 votes
24 votes
A triangle with vertices A(2, -2), B(-1, -1) and C(0, 2) is reflected across the y-axis and then dilated by a factor of 3 with the origin as the center of dilation. What is the x-coordinate of the A''?

User Oleksii Kyslytsyn
by
3.1k points

1 Answer

13 votes
13 votes


A^(\prime)^(\prime)(-6,-6)

Step-by-step explanation

Step 1

a) Plot the triangle

Step 2

now, do the transformations

Transformation 1

reflected across the y-axis:

The rule for a reflection over the y -axis is


(x,y)\Rightarrow(-x,y)

hence


\begin{gathered} A(2,-2)\Rightarrow reflected\text{ y-axis}\Rightarrow A^(\prime)(-2,-2) \\ B(-1,-1)\operatorname{\Rightarrow}reflected\text{y-ax}\imaginaryI\text{s}\operatorname{\Rightarrow}B^(\prime)(1,-1) \\ C(0,2)\operatorname{\Rightarrow}reflected\text{y-ax}\imaginaryI\text{s}\operatorname{\Rightarrow}C^(\prime)(0,2) \end{gathered}

so

Step 3

transformation 2:

b)dilated by a factor of 3 with the origin as the center of dilation:

A dilation with scale factor k centered at the origin will take each point

and


P(x,y)\Rightarrow dilated\text{ \lparen}K\text{ is the factor\rparen}\Rightarrow P^(\prime)(kx,yx)

so

in this case the factor is 3,hence


\begin{gathered} A^(\prime)(-2,-2)\Rightarrow dilated\text{ by a factor of 3}\Rightarrow A^(\prime)^(\prime)(-6,-6) \\ B^(\prime)(1,-1)\operatorname{\Rightarrow}dilated\text{ by a factor of 3}\Rightarrow B^(\prime)^(\prime)(3,-3) \\ C^(\prime)(0,2)\operatorname{\Rightarrow}dilated\text{ by a factor of 3}\Rightarrow C^{\prime^(\prime)}(0,6) \end{gathered}

so,the coordinate of teh A'' is


A^(\prime)^(\prime)(-6,-6)

I hope this helps you

A triangle with vertices A(2, -2), B(-1, -1) and C(0, 2) is reflected across the y-example-1
A triangle with vertices A(2, -2), B(-1, -1) and C(0, 2) is reflected across the y-example-2
A triangle with vertices A(2, -2), B(-1, -1) and C(0, 2) is reflected across the y-example-3
User Lucasz
by
3.1k points
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