Geometry Teachers Never Spend Time Trying to Find Materials for Your Lessons Again!
Join Our Geometry Teacher Community Today!
How to find the volume of a composite figure composed of cylinders
This volume problem involves two cylinders but one is inside the other cylinder and making an impression. In this problem you subtract the volume of the two composite figures instead of adding.
A composite of a cylinder inside a cylinder. Like a stck of washers or a stack of CD's. Same concept. First find the volume of the larger cylinder and subtract the volume of the smaller one. This time they are both circles so it will make the answer easier. We have a circle minis a circle. Think about your shapes and what you are subtracting. pi r squared times the height ( πr^2h - πr^2h) The formulas are the same, the only difference is that the radius will by different. What is the radius of the larger cylinder. It is 18. So eighteen squared times 12. Minus nine squared times 12.
18^2 x 12 = 3888π minus the other cylinder ( 9^2 x 12 = 972)
Can you subtract these. Yes because they both have a pi.
3888π - 972π = 2916π inches cubed.
So that is how you find the volume of composite figures when they are stacked on top of each other you add, and when one is inside the other and taking up space you subtract. Hope this was helpful.
You may also enjoy...
Area of a composite figure
Please watch: "Study Skills Teacher's Secret Guide to your Best Grades"
Tagged under: volume,composite figure,geometry,cylinder,volume cylinder,3d figure,volume 3d figures
Add multiple choice quizzes, questions and browse hundreds of approved, video lesson ideas for Clip
Make YouTube one of your teaching aids - Works perfectly with lesson micro-teaching plans
1. Students enter a simple code
2. You play the video
3. The students comment
4. You review and reflect
* Whiteboard required for teacher-paced activities
Carry out a quickfire formative assessment to see what the whole class is thinking
Create interactive presentations to spark creativity in class
Student teams can create and share collaborative presentations from linked devices
Turn any public video into a live chat with questions and quizzes