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grade8_transformation_geometry_quiz1 draws its questions at random from a bank of 13 questions, with full worked solutions for every one.
A few of the question types, with full solutions, so you know what to expect.
Which transformation is NOT rigid (does not keep the shape congruent)?
Answer: Enlargement
\(\text{Translations, reflections and rotations keep size and shape.}\)
\(\text{An enlargement changes the size, so the image is similar, not congruent.}\)
The point \(P(2;\ 3)\) is translated 3 right and 2 down. What is \(P'\)?
Answer: \((5;\ 1)\)
\(x: 2+3=5\)
\(y: 3-2=1\)
Point \(A(1;\ 4)\) maps to \(A'(-2;\ 6)\). What is the translation rule?
Answer: \((x-3;\ y+2)\)
\(\text{Subtract: image minus object.}\)
\(x: -2-1=-3 \text{ (3 left)}\)
\(y: 6-4=+2 \text{ (2 up)}\)
Reflect \(A(3;\ 2)\) in the x-axis. What is \(A'\)?
Answer: \((3;\ -2)\)
\(\text{x-axis reflection: } (x;\ y) \rightarrow (x;\ -y)\)
\(x \text{ stays, } y \text{ changes sign.}\)
Reflect \(B(-5;\ 1)\) in the y-axis. What is \(B'\)?
Answer: \((5;\ 1)\)
\(\text{y-axis reflection: } (x;\ y) \rightarrow (-x;\ y)\)
\(y \text{ stays, } x \text{ changes sign.}\)