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Perimeter Examples With Solutions

Worked perimeter examples you can copy into the home calculator to verify each total, with classroom and construction contexts.

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Geometry shapes and measuring tools for perimeter guides

Quick Answer

Substitute given lengths into the correct rule, compute, and state the answer with a length unit.

Formula

  • Rectangle: P = 2(l + w)
  • Polygon: sum of sides or n × s

Introduction

Examples turn formulas into numbers you can trust on site or on a test. Reading a rule is one step; seeing it applied twice builds the habit of checking units.

Perimeter Calculator mirrors every sample below when you enter the same dimensions, which is useful when you want to isolate whether the error was formula choice or arithmetic.

Work left to right. Keep units visible in your final sentence so graders and clients see that you answered a length question, not an area question.

Rectangle-heavy homework often appears alongside dedicated walkthroughs in our rectangle perimeter calculator guide when you need extra context on P = 2(l + w).

Three-side problems pair naturally with the triangle perimeter calculator article, which discusses scalene, isosceles, and equilateral labels.

Main Content

Why worked examples matter

An example shows which numbers belong in which symbols. That matters when a diagram lists four measurements but only three belong to the outer boundary.

Repeating examples across shapes trains formula selection. You stop reaching for 2πr when the figure is clearly a rectangle.

Real-world examples also teach estimation. If a fence quote around a backyard returns 3 ft total, you know something went wrong before you call a supplier.

Real-world examples

  • Fence: outer rectangle boundary
  • Frame: outer edge of opening
  • Track: lane boundary distance

Fence a rectangular garden 22 ft by 18 ft: you need 80 ft of railing along the outer edge, not the area of soil inside.

Molding around a square tabletop 3 ft per side: 12 ft of trim when the outline is a simple square and you cover every exposed edge.

Survey sketch with a quadrilateral: add four measured sides when no single shortcut formula fits because sides are unequal.

Running track: the distance along one lane follows the boundary curve and straight sections; break the path into pieces before you add.

Shape examples

Rectangle: l = 15 ft, w = 9 ft → P = 2(15 + 9) = 48 ft for molding along every wall of a rectangular room outline.

Square: s = 6 m → P = 4(6) = 24 m around a square plaza edge.

Triangle: sides 5 cm, 12 cm, 13 cm → P = 30 cm. Notice the familiar right-triangle triple.

Regular pentagon: side 4 in → P = 5 × 4 = 20 in around a five-sided sign outline.

Circle: r = 10 cm → P ≈ 62.83 cm when π ≈ 3.14159 for tape along a round flower bed.

Trapezoid: sides 8, 10, 8, 12 ft → P = 38 ft when you must add every labeled edge.

FAQ

Should I round π in circle examples?
Follow your teacher or job standard. Many classes use 3.14; others keep π on the calculator until the final step.
Can one example use two formulas?
Yes. Composite boundaries may add a semicircle to a rectangle. Label each piece, find each partial perimeter, then sum.
How many examples should I practice?
At least one per shape you expect on a quiz. Mix shapes so you practice selection, not just repetition of the same rule.

Conclusion

Practice a few shapes, then mix problems that force you to choose the right rule before you touch a calculator.

Confirm totals on the calculator when you want instant feedback.

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