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Geometry Transformations Calculators


Samuel Dominic Chukwuemeka
I greet you this day,
First: read the notes.
Second: view the Videos
Third: solve the questions/solved examples.
Fourth: check your solutions with my thoroughly-explained solutions.
Fifth: check your answers with the calculators as applicable.

You are encouraged to: solve the questions graphically (by construction); verify the solutions algebraically (by formulas); then use the calculators to check your answers.
I wrote the codes for these calculators using Javascript, a client-side scripting language. Please use the latest Internet browsers. The calculators should work.
At the moment, only the calculators for the Translations, Reflections, and Rotations are completed. Please check back for the remaining ones later.
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Samuel Chukwuemeka (Samdom For Peace) B.Eng., A.A.T, M.Ed., M.S


  • Translation (Sliding or Gliding)
  • For any point, (x1, y1);
  • A translation vector of <x, y> is the same as the translation rule of (x1 + x, y1+y)
  • Say:
    preimage = (x1, y1),
    translation vector = <x, y>,
    image = (x2, y2);
    then:
    x2 = x1 + x
    y2 = y1 + y
  • Translated left or right:
    only the x-coordinate changes
    the y-coordinate remains

    Translated up or down:
    only the y-coordinate changes
    the x-coordinate remains
  • translated x units left:
    then:
    x2 = x1 - x
    y2 = y1
  • translated x units right:
    then:
    x2 = x1 + x
    y2 = y1
  • translated y units up:
    then:
    x2 = x1
    y2 = y1 + y
  • translated y units down:
    then:
    x2 = x1
    y2 = y1 - y

Given: preimage, translation vector

To Find: image

(, )

<, >



(, )

Given: image, translation vector

To Find: preimage

(, )

<, >



(, )


Given: preimage, image

To Find: translation vector

(, )

(, )



<,>

Given: preimage, translation rule

To Find: image

(, )

units



(, )


  • Reflection (Flipping)
  • On the x-axis, y-values are zero.
    Reflecting across the x-axis:
    y-coordinate changes, x-coordinate remains.
  • On the y-axis, x-values are zero.
    Reflecting across the y-axis:
    x-coordinate changes, y-coordinate remains.
  • Reflecting across the origin:
    both the x-coordinate and the y-coordinate changes.
  • Reflecting across the line: x = k (k is a constant):
    the x-coordinate changes, y-coordinate remains.
  • Reflecting across the line: y = k (k is a constant)
    the y-coordinate changes, x-coordinate remains.
  • Reflecting across the line: y = x:
    both the x-coordinate and the y-coordinate changes.
  • For any point, (x, y);
  • Reflection across the x-axis gives (x, -y)
  • Reflection across the y-axis gives (-x, y)
  • Reflection across the origin gives (-x, -y)
  • Reflection across the line: y = x gives (y, x)
  • Reflection across the line: y = k (k is a constant) gives (x, 2k - y)
  • Reflection across the line: x = k (k is a constant) gives (2k - x, y)

Given: preimage, line of reflection

To Find: image



(, )

Given: image, line of reflection

To Find: preimage

(, )



(, )


Given: preimage, image

To Find: line of reflection

(, )

(, )




  • Rotation (Turning)
  • A preimage is rotated about the center of rotation through an angle of rotation.
  • If the preimage is rotated in a counterclockwise direction, the angle of rotation is positive.
  • If the preimage is rotated in a clockwise direction, the angle of rotation is negative.
  • Given:
    the preimage (x, y),
    the center of rotation as the origin (0, 0),
    an angle of rotation, θ;
    the image would be (x', y')
    where:
    x' = x cosθ - y sinθ
    y' = y cosθ + x sinθ
  • For counterclockwise rotations, use the positive value of θ
  • For clockwise rotations, use the negative value of θ
  • Given:
    the preimage (x1, y1),
    the center of rotation as any point (x, y),
    an angle of rotation, θ;
    the image would be (x1', y1')
    where:
    x1' = (cosθ(x1 - x) - sinθ(y1 - y)) + x
    y1' = (cosθ(y1 - y) + sinθ(x1 - x)) + y

Given: preimage, center of rotation (about the origin), angle of rotation

To Find: image

(, )

()

°



(, )

Given: preimage, center of rotation (any point), angle of rotation

To Find: image

(, )

(, )

°



(, )

References


Chukwuemeka, S.D (2016, April 30). Samuel Chukwuemeka Tutorials - Math, Science, and Technology. Retrieved from https://www.samdomforpeace.com

CrackACT. (n.d.). Retrieved from http://www.crackact.com/act-downloads/

CSEC Math Tutor. (n.d). Retrieved from https://www.csecmathtutor.com/past-papers.html

DLAP Website. (n.d.). Curriculum.gov.mt. https://curriculum.gov.mt/en/Examination-Papers/Pages/list_secondary_papers.aspx

GCSE Exam Past Papers: Revision World. Retrieved April 6, 2020, from https://revisionworld.com/gcse-revision/gcse-exam-past-papers