Explanation:
Definitions of all words in the paper:
- Radius (r): a straight line from the center to the circumference of a circle
- Diameter (d): the longest possible straight line passing from side to side through the center of a body or figure, especially a circle or sphere. This is calculated by 2 times radius.
- Circumference: the enclosing boundary of a curved geometric figure, especially a circle. This is calculated by using 2πr or πd
- Area: the region covered or enclosed within its boundary. This is calculated by using πr²
1)
Radius: Half the diameter. 40cm/2 = 20cm
Diameter: (given)
Circumference: Use πd. π * 40cm = 125.6cm
Area: Use πr². π * 20cm² = 1256cm²
2)
Radius: (given)
Diameter: 2 times radius. 8mm times 2 = 16mm
Circumference: Use πd. 16mm * π = 50.24mm
Area: Use πr². π * 8mm² = 200.96mm²
3)
Radius: (given)
Diameter: 2 times radius. 17cm times 2 = 34cm
Circumference: Use πd. 34cm * π = 106.76cm
Area: Use πr². π * 17cm² = 907.46cm²
4)
Radius: Half the diameter. 28mm/2 = 14mm
Diameter: (given)
Circumference: Use πd. 28mm * π = 87.92mm
Area: Use πr². π * 14mm² = 615.44mm²
5)
Radius: (given)
Diameter: Radius times 2. 10cm * 2 = 20cm
Circumference: Use πd. 20cm * π = 62.8cm
Area: Use πr². π * 10cm² = 314cm²
6)
Radius: (given)
Diameter: Radius times 2. 12mm * 2 = 24mm
Circumference: Use πd. 24mm * π = 75.36mm
Area: Use πr². π * 12mm² = 452.16mm²
7)
Radius: (given)
Diameter: Radius times 2. 2cm * 2 = 4cm
Circumference: Use πd. 4cm * π = 12.56cm
Area: Use πr². π * 2cm² = 12.56cm²
8)
Radius: Half the diameter. 12mm/2 = 6mm
Diameter: (given)
Circumference: Use πd. 12mm * π = 37.68mm
Area: Use πr². π * 6mm² = 113.04mm²
9)
Radius: Half the diameter. 8cm/2 = 4cm
Diameter: (given)
Circumference: Use πd. 8cm * π = 25.12cm
Area: Use πr². π * 4cm² = 50.24cm²