Geometry 3-5 Complete Lesson: Parallel Lines and Triangles

By Matt Richardson
Last updated about 3 years ago
27 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.

Solve It! Complete the following steps. Take and upload pictures to the canvas to document your progress after each step.

1. Draw and cut out a large triangle.
2. Tear off all three corners of the triangle.
3. Place the three corner pieces (that you tore off) so that they form adjacent angles.

Solve It! What is the sum of the meaures of the three angles of your triangle?
Enter only a number.

Solve It! Do all triangles have the same interior angle sum? How does the Solve It! activity support your answer?

Take Note: Summarize The Parallel Postulate. You may use the canvas to help illustrate your explanation.

Take Note: Summarize Theorem 3-11. You may use the canvas to help illustrate your explanation.

Take Note: Define auxiliary line. You may use the canvas to help illustrate your explanation.

Problem 1 Got It?

Take Note: Define remote interior angles. You may use the canvas to help illustrate your description.

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

Problem 2 Got It? Two angles of a triangle measure 53. What is the measure of an exterior angle at each vertex of the triangle?

Problem 3 Got It? In Problem 3, can you find m∠A without using the Triangle Exterior Angle Theorem?

Reasoning: Explain how the Triangle Exterior Angle Theorem makes sense based on the Triangle Angle-Sum Theorem.

Error Analysis: The measures of the interior angles of a triangle are 30, x, and 3x. Which of these methods for solving for x is incorrect?

Explain.

Review Lesson 3-4: If ∠1 and ∠2 are supplementary, what can you conclude about lines a and c?

Review Lesson 3-4:ABC and ∠CBD form a linear pair. If mABC = 3x + 20 and mCBD = x + 32, find the value of x. Enter only a number.

Review Lesson 3-4: ∠1 and ∠2 are supplementary. If ∠1 ≅ ∠2, find m∠1 and m∠2. Enter only a number.

Vocabulary Review: Identify the part of speech for the word alternate in each sentence on the right.

  • NOUN
  • ADJECTIVE
  • VERB
  • You vote for one winner an one alternate.
  • Your two friends alternate serves during tennis.
  • You and your sister babysit on alternate nights.

Use Your Vocabulary: Classify each statement as true or false.

  • A triangle is a polygon with three or more sides.
  • A tripod is a stand that has three legs.
  • In order to triple an amount, multiply it by three.
  • A triathlon is a race with two events - swimming & bicycling.
  • True
  • False

Reflection: Math Success