Grade 7 · Spatial Sense · Circles, Surface Area, and Volume
Connect Circles and Cylinders
A cylinder combines two circular bases with a curved surface that unfolds into a rectangle.
The big idea
The circle controls every cylinder formula
The rectangle in a cylinder net has length equal to the base circumference. Cylinder volume repeats the circular base area through the height.
Work it through
Find the volume when r = 3 cm and h = 8 cm
- 1. Find base area: A = πr² = π(3²) = 9π cm².
- 2. Multiply the base area by height.
- 3. V = 9π × 8 = 72π cm³.
- 4. Using π ≈ 3.14 gives about 226.08 cm³.