Join Free! Sign In UPLOAD
Science Science Math Math History History Social Studies Social Studies Language Arts Language Arts Educational Songs Kids Educational Songs
More
History Algebra Earth Science Geography Health PE Fractions Elementary Science Music Programming Languages Pre Calculus Chemistry Biology More
Open main menu TeacherTube.com
  • Join Free! Sign In UPLOAD
  • Close main menu

Remove Ads

Finding Area by Decomposing Rectangles

Middle School / Math / Geometry

raupr1974

Jan 21, 2019

1540 views

Geometry

Brief lesson/example of how to solve for area by decomposing new rectangles.

Today I?m going to talk about Finding area by decomposing rectangles.
So in this example, we have a large rectangle with a smaller rectangle cut out of it.
They are asking us to find the area of the shaded figure so I have colored in this part.
This part is not.
So we are only wanting to find the area of this part.
So the good part is that we do know the full size of the rectangle. It?s 9 cm by 7 cm. So if we start out with that shape, we could get that area.
And we take the area, 9x7 equals 63. That is the area of this whole shape. If the shape was still in there, not cut out.
So, I?m going to put 63 here down in my equation.
Alright, so now we have 63 minus something equals the total sq. cm.
So if we had this, and if we had to physically remove the area of this little shape, we will have to find the area of this little shape.
And we figure that out by multiplying the two sides.
3x2 equals 6. So I?m going to put that.
Now that I?ve got 2 values.
So now I?m going to subtract, 63 minus 6.
I?m going to put that on top of each other.
So we barrow. 13 minus 6 is 7. So we bring the 5 down. It?s 57.
So 63 minus 6 is 57 sq. cm.
So the area is 57 sq. cm.
Again, that was Finding area by decomposing rectangles.

Remove Ads

Remove Ads

Related categories

Middle School
Math
Algebra
Pre-Algebra
Middle School > Math > Geometry
Teaching w/ Technology-EDST750
Teaching w/ Technology-EDST750
Corresponding Angles Postulate
Corresponding Angles Postulate
9/30 Angles
9/30 Angles
Volume of a Cylinder example for TDT1 Task 3 Multimedia
Volume of a Cylinder example for TD...
Unit 1 Lesson 1
Unit 1 Lesson 1
Perimeters and Areas using Distance #1-4 of 16
Perimeters and Areas using Distance...
Unit 8 Vocabulary
Unit 8 Vocabulary
Area of Rectangles with Fractional Side Lengths
Area of Rectangles with Fractional ...
Area Formula Notes
Area Formula Notes
Area Formula Notes
Area Formula Notes
Middle School > Math
Exercises to Accompany "Solving Quadratic Equations By Completing the Square_Part 1"_1
Exercises to Accompany "Solving Qua...
5.1 Adv Perimeter & Area
5.1 Adv Perimeter & Area
Teaching w/ Technology-EDST750
Teaching w/ Technology-EDST750
Solving Logarithmic Equations Part 2
Solving Logarithmic Equations Part ...
Multiplying and Dividing Rational Expressions (8.4)
Multiplying and Dividing Rational E...
Corresponding Angles Postulate
Corresponding Angles Postulate
Perimeter & Area- Video 7
Perimeter & Area- Video 7
Perimeter & Area- Video 6
Perimeter & Area- Video 6
Perimeter & Area-Video 5
Perimeter & Area-Video 5
9/30 Angles
9/30 Angles
Middle School
French-Indian War Notes
French-Indian War Notes
PBL RESEARCH LESSON
PBL RESEARCH LESSON
PBL Research Lesson
PBL Research Lesson
Creating Your Portfolio Checklist
Creating Your Portfolio Checklist
Grammar Girl To the Rescue
Grammar Girl To the Rescue
Perimeter & Area- Video 7
Perimeter & Area- Video 7
Perimeter & Area- Video 6
Perimeter & Area- Video 6
Perimeter & Area-Video 5
Perimeter & Area-Video 5
Perimeter & Area-Video4
Perimeter & Area-Video4
Perimeter & Area-Video3
Perimeter & Area-Video3
  • Contact Us
  • Help and FAQ
  • Privacy Policy
  • Terms
  • California - Do Not Sell My Personal Information
  • California - CCPA Notice
© 2025 TeacherTube. All Rights Reserved.