Cylinders
Think of a cylinder as a tin can - it's got a circular top and bottom with curved sides connecting them. The volume formula is π r² h, where r is the radius and h is the height.
For surface area, you need to add up all the surfaces: the curved side plus the two circular ends. The formula becomes 2πrh + 2πr². The first part (2πrh) gives you the curved surface, whilst the second part (2πr²) covers both circular ends.
Let's say you've got a cylinder with radius 5cm and height 15cm. For surface area: 2 × π × 5 × 15 + 2 × π × 5² = 628cm². For volume of a water tank with radius 25cm and height 120cm: π × 25² × 120 = 235,500cm³.
Quick tip: Remember that volume always uses cubic units (cm³) whilst surface area uses square units (cm²).
