Illustrative Mathematics - Geometry - Mathematics - Unit 2 - Lesson 1 - Formative Library | Library

When rectangle ABCD is reflected across line EF, the image is DCBA. How do you know that segment  is congruent to segment DC?

Congruent parts of congruent figures are corresponding.

A rectangle has 2 pairs of parallel sides.

Corresponding parts of congruent figures are congruent.

Any 2 sides of a rectangle are congruent.

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Triangle FGH is the image of isosceles triangle FEH after a reflection across line HF. Select all the statements that are a result of corresponding parts of congruent triangles being congruent.

EFGH is a rectangle.

EFGH has 4 congruent sides.

Angle FEH is congruent to angle FGH.

Diagonal FH is perpendicular to side FE.

Diagonal FH bisects angles EFG and EHG.

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Reflect right triangle ABC across line BC. Classify triangle ACA' according to its side lengths. Explain how you know.

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Triangles FAD and DCE are translations of triangle ABC
Select all the statements that must be true.

The measure of angle DAC is the same as the measure of angle BCA.

Triangle ADC is a reflection of triangle FAD.

Line AD is parallel to line BC.

Points B, A, and F are collinear.

The measure of angle CED is the same as the measure of angle FAD.

The measure of angle BCA is the same as the measure of angle CED.

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Triangle ABC is congruent to triangles BAD and CEA.
Explain why points D, A, and E are collinear.
Explain why line DE is parallel to line BC.

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Identify a figure that is the result of a rigid transformation of quadrilateral ABCD.
Describe a rigid transformation that would take ABCD to that figure.

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This lesson is from Illustrative Mathematics. Geometry, Unit 2, Lesson 1. Internet. Available from https://curriculum.illustrativemathematics.org/HS/teachers/2/2/1/preparation.html ; accessed 29/July/2021.

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