Measure circles, parallelograms, and 3D solids — finding circumference, area, and volume with the right formulas.
A circle's circumference (perimeter) is found using C = 2πr, and its area using A = πr², where r is the radius. Using π ≈ 22/7 or 3.14 makes calculations practical.
Find the circumference of a circle with radius 7cm. (Use π = 22/7)
2 × 22/7 × 7 = 44cm
Find the area of a circle with radius 14cm. (Use π = 22/7)
22/7 × 14 × 14 = 616 square cm
For a cuboid: Volume = length × width × height, and Total Surface Area = 2(lw + wh + lh). For a cube, where all sides are equal: Volume = side³, and Total Surface Area = 6 × side².
Find the volume of a cuboid 8cm × 5cm × 4cm.
8 × 5 × 4 = 160 cubic cm
Find the volume of a cube with side 6cm.
6³ = 216 cubic cm
1. Find the circumference of a circle with radius 21cm. (Use π = 22/7)
2. Find the area of a circle with radius 7cm. (Use π = 22/7)
3. Find the volume of a cuboid 10cm × 6cm × 5cm.
4. Find the total surface area of a cube with side 5cm.
5. A cuboid water tank is 2m long, 1.5m wide, and 1m high. Find its volume in cubic meters.