Note:
Images with coordinates or original and translated triangles are attached.
Answer:
The coordinates for the given triangle are A(6,3), B(6,-3) and C(-2,-3), respectively.
Let us translate this triangle by -6 units along the x-axis and +3 units along the y-axis. This means that 6 will be subtracted from each of the abcissas (x-points) and 3 will be added to each ordinates (y-points). Hence, our translated triangle will have the following coordinates: A'(0,6), B'(0,0) and C'(-8,0), respectively.
Now to prove that both triangles are congruent, we use the SSS postulate, which states that:
<em>"If three sides of one triangle are congruent to three sides of another triangle, then the triangles are congruent."</em>
Distance between two point P1 and P2 will be:

Now using distance formula to find sides of triangle ABC and triangle A'B'C'.
For Triangle ABC:
|AB| = 
|AC| = 
|BC| = ![\sqrt{(-2-6)^2+[-3-(-3)]^2} =\;8\;units](https://tex.z-dn.net/?f=%5Csqrt%7B%28-2-6%29%5E2%2B%5B-3-%28-3%29%5D%5E2%7D%20%3D%5C%3B8%5C%3Bunits)
For Triangle A'B'C':
|A'B'| = 
|A'C'| = 
|B'C'| = 
Hence, as the distances are equal, the two triangles are congruent by SSS postulate.