standard_description: Prove theorems about parallelograms. Theorems include: opposite sides are congruent, opposite angles are congruent, the diagonals of a parallelogram bisect each other, and conversely, rectangles are parallelograms with congruent diagonals.
problem_activity: Task
Mr. Watkins asked his students to draw a line of symmetry for a circle
with center $O$ pictured below:
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Lisa drew the picture below. Is Lisa correct?
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Brad drew the picture below. Is Brad's picture correct?
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How many lines of symmetry does a circle have? Explain.
Explain why  each line of symmetry divides the circle in half.
Explain why each line of symmetry for the circle must go through the center.


aligns: no