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CanadaON
Grade 10

Transformations and similarity

Lesson

In Changing Shapes, we looked at how congruent shapes may be transformed in one or more ways on a number plane. We can also transform similar shapes. These similar shapes will be dilated by a scale factor (ie. enlarged or reduced by a certain ratio) in addition to the transformation. The video attached to the examples below explains this process.


Examples

Question 1

Question 2

Consider the quadrilateral with vertices at $A$A$\left(-3,-3\right)$(3,3), $B$B$\left(-3,3\right)$(3,3), $C$C$\left(3,3\right)$(3,3) and $D$D$\left(3,-3\right)$(3,3), and the quadrilateral with vertices at $A'$A$\left(-9,-9\right)$(9,9), $B'$B$\left(-9,9\right)$(9,9), $C'$C$\left(9,9\right)$(9,9) and $D'$D$\left(9,-9\right)$(9,9).

  1. Are the two rectangles similar, congruent or neither?

    congruent

    A

    similar

    B

    neither

    C
  2. What is the transformation from rectangle $ABCD$ABCD to rectangle $A'B'C'D'$ABCD?

    dilation

    A

    reflection

    B

    rotation

    C

    translation

    D
  3. What is the scale factor of the dilation of rectangle $ABCD$ABCD to rectangle $A'B'C'D'$ABCD?

Question 3

 

Outcomes

10P.MT1.02

Determine the lengths of sides of similar triangles, using proportional reasoning

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