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Geometry 10-1 Complete Lesson: Areas of Parallelograms and Triangles

By Matt Richardson

Last updated about 3 years ago

30 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! A stage is being set up for a concert at the arena. The stage is made up of blocks with tops that are congruent right triangles. The tops of the blocks, when put together, make an 8 ft-by-8 ft square. The band has requested that the stage be arranged to form the shape of an arrow. Draw a diagram that shows how the stage could be laid out in the shape of an arrow with an area of at least 1000 ft² but no more than 1400 ft². (You may use more blocks than shown in the picture.)

Problem 1 Got It?

Problem 2 Got It?

Problem 3 Got It?

Problem 4 Got It?

Writitng: How can you show that a parallelogram and a rectangle with the same bases and heights have equal areas?

Analysis: ▱ABCD is divided into two triangles along diagonal AC. If you know the area of the parallelogram, how do you find the area of △ABC?

Review Lesson 9-7: Are the figures similar? If so, describe the similarity transformation.

Review Lesson 9-7: Are the figures similar? If so, describe the similarity transformation.

Review Lesson 10-1: Write the formula for the area of a rectangle.

Review Lesson 10-1: Write the formula for the area of a triangle.

∠APE

∠APN

∠PAN

∠PNA

∠EPN

∠ANT

Review Lesson 10-1: Find the area of the trapezoid by using the formulas for area of a rectangle and area of a triangle. Enter your response in this format: 23.5 square units

Review Lesson 10-1: Find the area of the trapezoid by using the formulas for area of a rectangle and area of a triangle. Enter your response in this format: 23.5 square units

Review Lesson 10-1: Find the area of the trapezoid by using the formulas for area of a rectangle and area of a triangle. Enter your response in this format: 23.5 square units

Vocabulary Review: Complete each sentence. Use each word only once.

parallel
quadrilateral
rectangles

All parallelograms are __?__.
All parallelograms have opposite sides __?__.
Some parallelograms are __?__.

Enter only a number. Use decimal form if necessary.

Enter only a number. Use decimal form if necessary.

Enter only a number. Use decimal form if necessary.

Reflection: Math Success