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Cogito

Geometry · Chapter 2 · Lesson 1

Practice Worksheet

Rigid Motions and Symmetry

Moves that preserve everything but position.

10 problems · about 19 minutes · G-CO.A.2, G-CO.A.3, G-CO.A.5

NameDate

Figure — use these to answer the problems

Rotate the shape and compare with the dashed original.
Rotate by degrees90
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

2 problems

  1. From “Angles in Polygons”

    Interior sum of a heptagon (7 sides), in degrees?

    Answer

  2. From “Angle Pairs and Parallel Lines”

    Co-interior with 125°, lines parallel. What is it?

    Answer

Warm Up

Straightforward practice. Get the method working first.

4 problems

  1. A regular octagon maps onto itself after how many degrees, at minimum?

    Answer

  2. Two reflections in parallel lines compose to what?

    • A translation.
    • A rotation.

  3. Lines of symmetry in an equilateral triangle?

    Answer

  4. A regular pentagon maps onto itself after how many degrees, at minimum?

    Answer

Build It Up

The same ideas with more to keep track of.

2 problems

  1. Do rigid motions change side lengths?

    • No.
    • Yes.

  2. Lines of symmetry in a rectangle that is not a square?

    Answer

Stretch Yourself

Mixed problems. Work out what kind of question it is before you start.

2 problems

  1. The Square

    How many lines of symmetry does a square have?

    Answer

  2. The Rotation

    A regular hexagon maps onto itself after a rotation of how many degrees, at minimum?

    Answerdegrees