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Geometry 4-5 Complete Lesson: Isosceles and Equilateral Triangles

By Matt Richardson
Last updated almost 3 years ago
31 Questions
Note from the author:
A complete formative lesson with embedded slideshow, mini lecture screencasts, checks for understanding, practice items, mixed review, and reflection. I create these assignments to supplement each lesson of Pearson's Common Core Edition Algebra 1, Algebra 2, and Geometry courses. See also mathquest.net and twitter.com/mathquestEDU.

Visit this URL to create a copy of the Google Drawing and complete the item that follows: https://docs.google.com/drawings/d/15TaBfWflkEageasFgoi31Yb9Ql_t1rssKR5yFQhGa5Q/copy

Solve It! The triangles of the same color in the Google Drawing you copied above are congruent. Complete the following steps.

1. Arrange the triangles to form one large triangle using the Google Drawings to drag, flip, and rotate individual triangles, but do not resize them.
2. Take a screenshot of your final triangle and upload the image to the canvas.

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Solve It! Classify the large triangle you created in the item above by its sides.

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Solve It! Which of these measurements represent interior angles in the large triangle you created?
Select all that apply.

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Take Note: Describe the vertex angle of an isosceles triangle. You may also illustrate your description on the canvas.

Take Note: Describe the base angles of an isosceles triangle. You may also illustrate your description on the canvas.

Take Note: Describe the legs of an isosceles triangle. You may also illustrate your description on the canvas.

Take Note: Describe the base of an isosceles triangle. You may also illustrate your description on the canvas.

Take Note: Summarize The Isosceles Triangle Theorem. You may use the canvas to help illustrate your description.

Take Note: Summarize The Converse of the Isosceles Triangle Theorem. You may use the canvas to help illustrate your description.

Problem 1 Got It? Is ∠WVS congruent to ∠S ?

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Problem 1 Got It? Is segment TR congruent to segment TS ?

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Problem 1 Got It? Reasoning: Can you conclude that △RUV is isosceles?

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Take Note: Summarize Theorem 4-5. You may use the canvas to help illustrate your description.

Problem 2 Got It?

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Take Note: Define corollary.

Take Note: Summarize The Corollary to Theorem 4-3. You may use the canvas to help illustrate your description.

Take Note: Summarize The Corollary to Theorem 4-4. You may use the canvas to help illustrate your description.

Problem 3 Got It?

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Reasoning: What is the relationship between sides and angles for each type of triangle?

a. isosceles
b. equilateral

Error Analysis: Claudia drew an isosceles triangle. She asked Sue to mark it. Explain why the marking of the diagram is incorrect.

Review Lesson 2-1: Find the next two terms of the sequence.

Review Lesson 4-2: Can you conclude that the two triangles are congruent? Explain.

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Review Lesson 4-2: Can you conclude that the two triangles are congruent? Explain

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Vocabulary Review: Respond to each item on the right with the correct item fron the left.

  • 1
  • 2
  • 3
  • acute
  • obtuse
  • right
  • An equilateral triangle has __?__ congruent sides.
  • The angles of an equilateral triangle are __?__.
  • This is an example of an equilateral triangle.

Use Your Vocabulary: Classify each of the triangles.

Triangles may be placed in more than one category.

  • △A
  • △B
  • △C
  • △D
  • △E
  • Equilateral
  • Isosceles
  • Right

Reflection: Math Success

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