To find the perimeter of a shape, you add up the lengths of all its sides. For example, if you have a triangle with sides measuring 11, 11, and 9 units, the perimeter is 11+11+9=3111+11+9=3111+11+9=31 units

. For regular polygons (shapes with all sides equal), you can multiply the length of one side by the number of sides. For instance, the perimeter of a square with side length sss is 4×s4\times s4×s, and for a pentagon with side length sss, it is 5×s5\times s5×s

. For rectangles, the perimeter is calculated using the formula:

P=2×(L+W)P=2\times (L+W)P=2×(L+W)

where LLL is the length and WWW is the width

. For circles, the perimeter is called the circumference and is found by:

C=2πrC=2\pi rC=2πr

where rrr is the radius and π≈3.14\pi \approx 3.14π≈3.14

. In summary:

• Add all side lengths for any polygon.
• Multiply side length by number of sides for regular polygons.
• Use P=2(L+W)P=2(L+W)P=2(L+W) for rectangles.
• Use C=2πrC=2\pi rC=2πr for circles.

Always include the correct units in your final answer