To find the perimeter of a shape when you know the length of its edges, you need to:

1. Identify the shape: Different shapes have different formulas for perimeter.

   • Rectangle: The perimeter $P$ is given by: $P = 2 \times (\text{length} + \text{width})$

   • Square: Since all four edges are the same, the perimeter $P$ is: $P = 4 \times \text{side length}$

   • Triangle: If you know the lengths of all three sides $a$, $b$, and $c$, the perimeter $P$ is: $P = a + b + c$

   • Polygon: For any polygon, the perimeter is the sum of the lengths of all its sides. If a polygon has $n$ sides, and each side is of length $s$, the perimeter $P$ is: $P = n \times s$ (for regular polygons).

2. Measure the sides: Once you've identified the shape and know how long each edge is, just apply the corresponding formula.

Do you have a specific shape or measurement you’d like help with? Let me know if you'd like more details!

Related Questions:

1. How do you calculate the perimeter of a circle (circumference)?
2. How can you find the perimeter of a hexagon if each side is equal?
3. What's the difference between the perimeter and area of a shape?
4. How do you calculate the perimeter of a trapezoid?
5. How does the perimeter formula change if the sides are unequal?

Tip:

For irregular polygons, simply sum the lengths of all the sides to find the perimeter.