Geometric transformations (translation) — KCSE Mathematics

KCSE Mathematics · 110 practice questions · 3 syllabus objectives · 3 revision lessons

36 easy37 medium37 hard

Last updated · Aligned to the KNEC KCSE syllabus

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Describe a translation using a column vector; find the image of a point or shape under a given translation

Find the translation vector that maps one point or shape to another; combine two successive translations

Geometric transformations (translation)

Revision Notes

Concise lesson notes for Geometric transformations (translation), written to the KCSE Mathematics marking standard. Read the first lesson free below.

Understanding Translation in Geometry

A translation in geometry refers to shifting a point or shape in a specific direction without changing its size or orientation. It is described using a column vector. The vector indicates how far to move in the x-direction (horizontal) and y-direction (vertical).

For example, a translation vector of ( \begin{pmatrix} 3 \ 2 \end{pmatrix} ) means to move 3 units right and 2 units up. To find the image of a point under a translation, simply add the vector to the original coordinates.

Example: If point A has coordinates (2, 4) and is translated using the vector ( \begin{pmatrix} 3 \ 2 \end{pmatrix} ):

  • New coordinates = ( (2 + 3, 4 + 2) = (5, 6) ) Thus, the image of point A after translation is (5, 6).

For shapes, apply the same vector to each vertex to find the new positions.

Key points to remember

  • Translation shifts points or shapes without rotation or resizing.
  • A translation is described using a column vector.
  • Add the translation vector to the original coordinates.
  • Each vertex of a shape is translated individually.
  • The direction and distance are defined by the vector.

Worked example

Translate point B (1, 2) using vector ( \begin{pmatrix} -4 \ 3 \end{pmatrix} ). New coordinates = ( (1 - 4, 2 + 3) = (-3, 5) ).

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More lessons in this topic

Lesson 2: Understanding Translation Vectors

Objective: Find the translation vector that maps one point or shape to another; combine two successive translations

In geometry, translation refers to moving a point or shape from one position to another without changing its size, shape, or orientation. The translation vector indicates the direction and distance of this movement.

To find the translation vector that maps point A(x₁, y₁) to point B(x₂, y₂), use the formula:

Translation vector = (x₂ - x₁, y₂ - y₁)

For example, if point A is at (2, 3) and point B is at (5, 7):

  • Calculate the translation vector:
    • x-component: 5 - 2 = 3
    • y-component: 7 - 3 = 4
  • Therefore, the translation vector is (3, 4).

When combining two successive translations, say T₁ = (a, b) and T₂ = (c, d), the resultant translation vector R is:

R = (a + c, b + d)

This means you simply add the corresponding components of the two vectors. For instance, if T₁ = (2, 3) and T₂ = (1, 4):

  • R = (2 + 1, 3 + 4) = (3, 7).
  • Translation moves points without altering their characteristics.
  • Find translation vector using (x₂ - x₁, y₂ - y₁).
  • Combine translations by adding their vectors' components.

Given A(1, 2) and B(4, 5), find the translation vector.

  • Translation vector = (4 - 1, 5 - 2) = (3, 3).
Lesson 3: Understanding Geometric Translations

Objective: Geometric transformations (translation)

Geometric translation is a type of transformation that slides a shape from one position to another without changing its size, shape, or orientation. In a translation, every point of the shape moves the same distance in the same direction.

Key features of translation:

  • Vector Notation: Translations can be represented using vectors, e.g., (3, 2) means move right 3 units and up 2 units.
  • Coordinate Change: If a point A(x, y) is translated by vector (a, b), the new coordinates A' will be (x + a, y + b).

Example:

  • Given: Point A(2, 3) is translated by vector (4, -1).
  • Solution: A' = (2 + 4, 3 - 1) = (6, 2). Thus, A' is the new position of point A after translation.
  • Translation slides a shape without altering its size or orientation.
  • Every point moves the same distance in the same direction.
  • Translations are represented using vectors.
  • New coordinates are found by adding vector components.

Translate point B(1, 2) by vector (3, 5). New position B' = (1 + 3, 2 + 5) = (4, 7).

Sample Questions

Read 3 questions and answers free. Sign up to access all 110 questions with full KNEC-style marking schemes and a personalised study plan.

1
easySHORT ANSWER4 marks

A point A(3, 4) is translated by the vector (2, -1). (a) State the coordinates of the image A' after the translation. (2 marks) (b) If point B(1, 2) undergoes the same translation, find the coordinates of the image B'. (2 marks)

Answer & marking scheme

Part (a) — 2 marks
A' = (3 + 2, 4 - 1) = (5, 3) (2 mks)
Part (b) — 2 marks
B' = (1 + 2, 2 - 1) = (3, 1) (2 mks)
2
easySHORT ANSWER3 marks

Triangle DEF has vertices D(2, 3), E(4, 5), and F(6, 7). State the coordinates of the image D'E'F' after a translation by the vector (3, -2). (3 marks)

Answer & marking scheme

Part (a) — 3 marks
D' = (2 + 3, 3 - 2) = (5, 1) (1 mk)
E' = (4 + 3, 5 - 2) = (7, 3) (1 mk)
F' = (6 + 3, 7 - 2) = (9, 5) (1 mk)
3
easySHORT ANSWER3 marks

Triangle PQR has vertices P(30, 88), Q(34, 50) and R(22, 82). (a) Find the image P'Q'R' under translation by vector (23, 34). [2 marks] (b) Find the translation vector that maps P to P' where P'= (54, 89). [1 mark]

Answer & marking scheme

Part (a) — 3 marks
Each vertex correctly translated by adding (tx, ty) (1 mk)
Image vertices P'Q'R' all correct (1 mk)
Translation vector = P' − P = (ppx−px, ppy−py) correct (1 mk)
4

Triangle PQR has vertices P(23, 26), Q(73, 49) and R(22, 11). (a) Find the image P'Q'R' under translation by vector (49, 99). [2 marks] (b) Find the translation vector that maps P to P' where P'= (50, 20). [1 mark]

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Frequently asked questions

What does the KCSE Mathematics topic "Geometric transformations (translation)" cover?

Geometric transformations (translation) covers Describe a translation using a column vector; find the image of a point or shape under a given translation; Find the translation vector that maps one point or shape to another; combine two successive translations; Geometric transformations (translation), all aligned to the official KNEC KCSE Mathematics syllabus.

How many practice questions are available for Geometric transformations (translation)?

HighMarks has 110 Geometric transformations (translation) practice questions for KCSE Mathematics, each with a full marking scheme. The first 3 are free; sign up to access the rest, plus all KCSE mock exams and past papers.

Are these aligned with the KNEC KCSE syllabus?

Yes. Every objective on this page is taken directly from the official KNEC KCSE Mathematics syllabus. Practice questions match the KCSE exam format and are graded against the standard KNEC marking scheme.

How should I revise Geometric transformations (translation) for the KCSE exam?

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