What we need: Perimeter of the outer rectangle including the path
Given: Inner garden: length = 24 ft, width = 16 ft; Path width = 4 ft
- Calculate the dimensions of the outer rectangle
- Add the path width to both length and width (on both sides)
- Use the rectangle perimeter formula: P = 2 × (length + width)
- Substitute the outer dimensions
- Calculate the result
The perimeter of the outer edge of the path is 112 feet.
• Compound Shape Perimeter: Focus on outer edges only
• Dimension Addition: Path adds to both sides of each dimension
• Rectangle Perimeter: P = 2 × (length + width)
What we need: Perimeter of the compound shape
Given: Square side = 10 cm; Rectangle: length = 10 cm, width = 6 cm
The perimeter of the compound shape is 42 centimeters.
• Compound Shape Perimeter: Only count outer edges
• Shared Sides: Don't count sides that are internal to the shape
• Visual Approach: Trace the outer edge to identify all sides
What we need: Perimeter of an irregular pentagon
Given: Side₁ = 8 in, Side₂ = 10 in, Side₃ = 7 in, Side₄ = 9 in, Side₅ = 12 in
The perimeter of the pentagon is 46 inches.
• Polygon Perimeter: P = sum of all side lengths regardless of shape
• Irregular Shapes: Add each side individually
• Units: Ensure all sides are measured in the same unit
What we need: Perimeter of the outer rectangle including the deck
Given: Pool: length = 20 ft, width = 12 ft; Deck width = 3 ft
The perimeter of the outer edge of the deck is 88 feet.
• Compound Shape Perimeter: Focus on outer edges only
• Dimension Addition: Deck adds to both sides of each dimension
• Rectangle Perimeter: P = 2 × (length + width)
What we need: Perimeter of the L-shaped compound figure
Given: Rectangle 1: 15 ft × 8 ft; Rectangle 2: 10 ft × 6 ft; Joined along 8 ft side
The perimeter of the L-shaped garden is 58 feet.
• L-Shape Perimeter: Add all outer edges only
• Internal Lines: Don't count shared sides between rectangles
• Visualization: Draw and trace the outer boundary to identify all sides
Problem A: A rectangular field is 50 meters long and 30 meters wide. A path of uniform width runs around the field. If the area of the path is 336 square meters, find the perimeter of the outer edge of the path.
Problem B: A hexagonal garden has sides of 12 feet, 15 feet, 10 feet, 14 feet, 11 feet, and 13 feet. What is the perimeter?
Problem C: Two squares, one with side 8 cm and another with side 5 cm, are placed side by side. What is the perimeter of the resulting figure?
A rectangular room measures 18 feet by 14 feet. A hallway of width 4 feet surrounds the room on all sides. What is the perimeter of the outer edge of the hallway?
Solution: Outer length = 18 + 8 = 26 ft, Outer width = 14 + 8 = 22 ft, P = 2(26 + 22) = 96 ft
A T-shaped figure consists of a 12-inch by 8-inch rectangle with a 6-inch by 4-inch rectangle centered on top. What is the perimeter of the entire figure?
Solution: Count outer edges: 12 + 8 + 6 + 4 + 6 + 8 + 12 + 4 = 60 inches
An octagonal stop sign has 8 equal sides, each measuring 12 inches. What is the perimeter?
Solution: P = 8 × 12 = 96 inches
Directions: Solve each problem by finding the perimeter. Show your work and include units in your answer.
Advanced Techniques:
- Break complex shapes into simpler parts
- Focus only on outer edges for compound shapes
- Account for paths and borders properly
- Double-check your calculations
- Verify your answer makes sense