Given:
The vertices of a triangle are R(3, 7), S(-5, -2), and T(3, -5).
To find:
The vertices of the triangle after a reflection over x = -3 and plot the triangle and its image on the graph.
Solution:
If a figure reflected across the line x=a, then
![(x,y)\to (-(x-a)+a,y)](https://img.qammunity.org/2022/formulas/mathematics/high-school/9nw54sjw6wb3d2vxrjkfl7cjjt27nzpqdz.png)
![(x,y)\to (-x+a+a,y)](https://img.qammunity.org/2022/formulas/mathematics/high-school/io4tpc2bsahyek0z84incl3w93hx5o560g.png)
![(x,y)\to (2a-x,y)](https://img.qammunity.org/2022/formulas/mathematics/college/3wf53p9kbtgv6svoqtngotyfxy4taisxae.png)
The triangle after a reflection over x = -3. So, the rule of reflection is
![(x,y)\to (2(-3)-x,y)](https://img.qammunity.org/2022/formulas/mathematics/college/bseftjndf13tojqa9gd0a6dr1g2rezhwed.png)
![(x,y)\to (-6-x,y)](https://img.qammunity.org/2022/formulas/mathematics/college/cogh1jksemofhjuarrmal2lt7sv6e6ahz9.png)
The vertices of triangle after reflection are
![R(3,7)\to R'(-6-3,7)](https://img.qammunity.org/2022/formulas/mathematics/college/63i862dpp4vfsxi92qnmiv0rv6noix4hlt.png)
![R(3,7)\to R'(-9,7)](https://img.qammunity.org/2022/formulas/mathematics/college/ohtaferqso9g11875hs63u66trbm80y7kt.png)
Similarly,
![S(-5,-2)\to S'(-6-(-5),-2)](https://img.qammunity.org/2022/formulas/mathematics/college/ho67vz1n65eydayyvvk9jnffwmhz2gmviz.png)
![S(-5,-2)\to S'(-6+5,-2)](https://img.qammunity.org/2022/formulas/mathematics/college/ci7rbjbbggdjlmdxv5yl1k96uj8uqlfo2t.png)
![S(-5,-2)\to S'(-1,-2)](https://img.qammunity.org/2022/formulas/mathematics/college/tgeadjpfldx0dsfrcayo3kwcega89shl7v.png)
And,
![T(3,-5)\to T'(-6-3,-5)](https://img.qammunity.org/2022/formulas/mathematics/college/xosibb32b17mqcufo72bza7047622ci4l4.png)
![T(3,-5)\to T'(-9,-5)](https://img.qammunity.org/2022/formulas/mathematics/college/t101arj8i7m7j6j6l33wk7gassek0owvny.png)
Therefore, the vertices of triangle after reflection over x=-3 are R'(-9,7), S'(-1,-2) and T'(-3,-5).