Math Lab
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Rectangle Perimeter and Area

Mensuration · Class VI

Drag length and breadth to see how a rectangle's perimeter and area change.

8 cm
type a value
130
5 cm
type a value
130
Live values
  • Perimeter26
  • Area40
  • Diagonal9.434
xy
  • Area as breadth varies

Formulas in this lab

  • Perimeter
    2(l+b)2(l + b)
  • Area
    l⋅bl \cdot b
  • Diagonal
    l2+b2\sqrt{l^2 + b^2}
Tip: With length fixed, the area grows as a straight line in breadth.

Frequently asked questions

▶What is the formula for area and perimeter of a rectangle?

Area is length times breadth, written l*b. Perimeter is twice the sum, written 2(l + b). For a rectangle of 8 cm by 5 cm, the area is 40 sq cm and the perimeter is 26 cm.

▶How do I use the rectangle area lab?

Slide l and b between 1 and 30 cm. The lab updates area and perimeter instantly. Try l = 10 and b = 4 to see area 40 sq cm and perimeter 28 cm, then double l to see how area also doubles but perimeter only goes up by 20 cm.

▶If I tile a 12 ft by 10 ft room with 2 ft by 2 ft tiles, how many tiles do I need?

Room area is 12 * 10 = 120 sq ft. Each tile is 2 * 2 = 4 sq ft. So 120 / 4 = 30 tiles. The same idea works for the lab: increase l and b and use the new area to plan a Diwali rangoli or a school notice board.

▶Area vs perimeter: which one is bigger?

They measure different things and cannot really be compared as numbers. Area uses square units like sq cm, while perimeter uses plain cm. A 1 cm by 1 cm square has area 1 but perimeter 4. A 10 cm square has area 100 but perimeter 40. The lab makes this contrast easy to see.