Let’s solve each shape’s perimeter step by step.
Perimeter = add up all the side lengths.
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1. Rectangle (9cm, 4cm, 9cm, 4cm)
Add: 9 + 4 + 9 + 4 =
26 cm
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2. Triangle (3mm, 11mm, 15mm)
Add: 3 + 11 + 15 =
29 mm
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3. Square (5mm on each side)
All 4 sides are 5mm → 5 + 5 + 5 + 5 =
20 mm
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4. Trapezoid (8m, 5m, 3m, 8m)
Add: 8 + 5 + 3 + 8 =
24 m
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5. Arrow-shaped figure (7cm, 2cm, 2cm, 7cm, 5cm)
Wait — let’s list all outer sides:
Top: 7cm
Right top slant: 2cm
Right bottom slant: 2cm
Bottom: 7cm
Left vertical: 5cm
→ Add: 7 + 2 + 2 + 7 + 5 =
23 cm
*(Note: The left side is only one side — 5cm — not two. The shape has 5 sides total.)*
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6. Equilateral triangle (6km each side)
6 + 6 + 6 =
18 km
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7. Right triangle (3km, 4km, 5km)
Add: 3 + 4 + 5 =
12 km
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8. Parallelogram (8cm, 4cm, 8cm, 4cm)
Opposite sides equal → 8 + 4 + 8 + 4 =
24 cm
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✔ All calculations double-checked.
Final Answer:
Perimeter of rectangle: 26 cm
Perimeter of first triangle: 29 mm
Perimeter of square: 20 mm
Perimeter of trapezoid: 24 m
Perimeter of arrow shape: 23 cm
Perimeter of equilateral triangle: 18 km
Perimeter of right triangle: 12 km
Perimeter of parallelogram: 24 cm
Parent Tip: Review the logic above to help your child master the concept of perimeter worksheet for grade 3.
