01 Key Concepts
Perimeter Definition
The total distance around the boundary of a two-dimensional shape.
Perimeter of a Rectangle
P = 2*(length + width), since opposite sides are equal.
Perimeter of a Square
P = 4*side, since all four sides are equal.
Perimeter of a Triangle
P = sum of all three side lengths.
Perimeter of Any Polygon
Simply add up the lengths of every side, regardless of the shape's regularity.
02 Key Formulas
- Rectangle: P = 2*(length + width)
- Square: P = 4*side
- Triangle/general polygon: P = sum of all sides
03 Solved Examples
Example 1 Find the perimeter of a rectangle with length 7 and width 3.
- Apply the formula: P = 2*(length+width) = 2*(7+3) = 2*10.
Answer: 20 units
Example 2 Find the perimeter of a square with side 6.
- Apply the formula: P = 4*side = 4*6.
Answer: 24 units
Example 3 Find the perimeter of a triangle with sides 5, 7, and 9.
- Add all three sides: 5+7+9.
Answer: 21 units
04 Practice Questions
1Find the perimeter of a rectangle with length 10 and width 4.
28
2Find the perimeter of a square with side 8.
32
3Find the perimeter of a triangle with sides 4, 5, 6.
15
4Find the perimeter of a pentagon with all sides 5.
25
5A rectangle has perimeter 30 and width 5. Find its length.
10 (30=2*(L+5))
📄 Perimeter — Downloadable Worksheet
10 questions with a full answer key. Grab the PDF to print, or try the interactive version in your browser.