Translations and dilations
Translate shapes using vectors and dilate shapes from the origin using a scale factor.
Worked examples
Translating a point using a vector
Straightforward
Problem
Translate point by the vector and state the coordinates of .
1
Add the horizontal component of the vector to the -coordinate.
2
Add the vertical component of the vector to the -coordinate.
3
Write the coordinates of the image.
Answer
Dilating a point from the origin
Moderate
Problem
Point is dilated from the origin by scale factor . State the coordinates of .
1
Write the dilation rule: multiply each coordinate by the scale factor .
where
2
Multiply the -coordinate by .
3
Multiply the -coordinate by .
4
Write the coordinates of the image.
Answer
Finding the scale factor and classifying a dilation
Challenging
Problem
Point is mapped to by a dilation from the origin. Find the scale factor and classify the transformation as an enlargement, reduction or congruent.
1
Find the scale factor by dividing an image coordinate by the corresponding original coordinate.
2
Verify using the -coordinates.
✓
3
Classify the dilation: since , the image is smaller than the original.
, so this is a reduction.
Answer
Scale factor ; the transformation is a reduction.
Practise
Q1·Straightforward
Point is translated by the vector . State the coordinates of .
Explanation
Add each component of the vector to the matching coordinate: and . So .
Q2·Straightforward
Point is translated by the vector . State the coordinates of .
Explanation
and . So .
Q3·Straightforward
Point is translated by the vector . State the coordinates of .
Explanation
and . So .
Q4·Straightforward
A rectangle has vertex . It is translated by the vector . State the coordinates of .
Explanation
and . So .
Q5·Moderate
Point is dilated from the origin by scale factor . State the coordinates of .
Explanation
A dilation from the origin by scale factor maps . With : and . So .
Q6·Moderate
Point is dilated from the origin by scale factor . State the coordinates of .
Explanation
and . So .
Q7·Moderate
Triangle has vertex . It is dilated from the origin by scale factor . State the coordinates of .
Explanation
and . So .
Q8·Moderate
Point is dilated from the origin by scale factor . State the coordinates of .
Explanation
and . So .
Q9·Challenging
Point is mapped to by a dilation from the origin. What is the scale factor?
Explanation
Scale factor . Check: ✓. The scale factor is .
Q10·Challenging
Point is mapped to by a dilation from the origin. What is the scale factor?
/
Explanation
Scale factor . Check: ✓. The scale factor is .
Q11·Challenging
Point is mapped to by a dilation from the origin. What is the scale factor?
/
Explanation
Scale factor . Check: ✓. The scale factor is .
Q12·Challenging
Triangle has side lengths cm, cm and cm. It is mapped to triangle with side lengths cm, cm and cm. Classify this transformation.
Explanation
The scale factor is . Since , the image is larger than the original, so the transformation is an enlargement.
Open Math
Translations and dilations
Space · MA4-GEO-C-01
Name:
Date:
Q1Straightforward
Point is translated by the vector . State the coordinates of .
Q2Straightforward
Point is translated by the vector . State the coordinates of .
Q3Straightforward
Point is translated by the vector . State the coordinates of .
Q4Straightforward
A rectangle has vertex . It is translated by the vector . State the coordinates of .
Q5Moderate
Point is dilated from the origin by scale factor . State the coordinates of .
Q6Moderate
Point is dilated from the origin by scale factor . State the coordinates of .
Q7Moderate
Triangle has vertex . It is dilated from the origin by scale factor . State the coordinates of .
Q8Moderate
Point is dilated from the origin by scale factor . State the coordinates of .
Q9Challenging
Point is mapped to by a dilation from the origin. What is the scale factor?
Q10Challenging
Point is mapped to by a dilation from the origin. What is the scale factor?
Q11Challenging
Point is mapped to by a dilation from the origin. What is the scale factor?
Q12Challenging
Triangle has side lengths cm, cm and cm. It is mapped to triangle with side lengths cm, cm and cm. Classify this transformation.
- A.Enlargement
- B.Reduction
- C.Congruent
- D.Reflection
Worked solutions and answers at openmath.au/year-8/properties-of-geometrical-figures/translations-and-dilations