Define congruence of plane shapes using transformations (ACMMG200)

LO:To determine if plane shapes are congruent.

  • How to measure the sides and angles of a plane shape..
  • What transformation is.


  • That shapes that have the same properties are congruent..


  • I can determine if two plane shapes are congruent.


Congruent means a shape that is exactly equal in size and shape.


Transformations are actions that you can take on an object to create congruent shapes.


Translations can also be called “slides”.

The initial picture is the exact same as the finishing picture.

The easiest way to look for translations is to pick one point on the starting picture and pick the exact same point on the finishing picture and count the number of moves.


Reflections can also be called “mirror images”

The finishing picture is “flipped” from the initial picture.

The points from the reflected picture is exactly the same distance (equidistant) from the line of reflection as the initial picture.

The distance between the green, red and blue dots are the same from the initial image to the reflected image.


Rotations can also be called “spins”.

The finishing picture is rotated on a point.

Any points on a straight line is the same distance away from the point of rotation.

Congruence Videos

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