= 2×15×6 + 2×15×12 + 2×6×12 12 m = 180 + 360 + 144 = 684 m2 6 m 15 m Cube: A cube is a special rectangular solid that has sides that all have the same length. So the surface area is side times side multiplied by 6 sides. SA = × × 6 or SA= 6s2 s s Example: SA= 6s3 = 6 × 7 × 7 7 cm = 294 cm2 7 cm 7 cm Cylinder: The surface area of a cylinder is a two part formula. The part multiplies 2 times π times the radius times the height for the side of the cylinder. This represents the area of side of the cylinder (it’s a rectangle). Then the top and bottom circles must be added. The area of each of these is π times the radius, times the radius or radius squared (r2). As there are 2 circles, this must be multiplied twice. SA = 2πrh + 2πr2 SA = 2 × × × + 2 × × × r h r r which means π π side top & bottom Example: SA = 2πrh + 2πr2 = 2 × × 3 × 9 + 2 × × 3 × 3 π π = 169.65 + 56.55 = 226.2 in2 r = 3 in h = 9 in
= 2×15×6 + 2×15×12 + 2×6×12 12 m = 180 + 360 + 144 = 684 m2 6 m 15 m Cube: A cube is a special rectangular solid that has sides that all have the same length. So the surface area is side times side multiplied by 6 sides. SA = s × s × 6 or SA= 6s2 Example: SA= 6s3 = 6 × 7 × 7 7 cm = 294 cm2 7 cm 7 cm Cylinder: The surface area of a cylinder is a two part formula. The part multiplies 2 times π times the radius times the height for the side of the cylinder. This represents the area of side of the cylinder (it’s a rectangle). Then the top and bottom circles must be added. The area of each of these is π times the radius, times the radius or radius squared (r2). As there are 2 circles, this must be multiplied twice. SA = 2πrh + 2πr2 which means SA = 2 × π × r × h + 2 × π × r × r side top & bottom Example: SA = 2πrh + 2πr2 = 2 × π × 3 × 9 + 2 × π × 3 × 3 = 169.65 + 56.55 = 226.2 in2 r = 3 in h = 9 in