Let's solve each shape one by one to calculate the
perimeter — which is the total length around the outside of a shape. We add up all the side lengths.
---
1. Rectangle
- Length = 12 cm
- Width = 7 cm
A rectangle has two pairs of equal sides:
- Two sides of 12 cm
- Two sides of 7 cm
Perimeter = 2 × (length + width)
= 2 × (12 + 7)
= 2 × 19
=
38 cm
✔ Answer: 38 cm
---
2. Square
- Side = 80 mm
All four sides of a square are equal.
Perimeter = 4 × side
= 4 × 80 mm
=
320 mm
✔ Answer: 320 mm
---
3. Right Triangle
- Sides: 10 cm, 7 cm, and 6 cm
We are given all three sides, so just add them:
Perimeter = 10 + 7 + 6 =
23 cm
✔ Answer: 23 cm
>
✔ Note: This is a right triangle (since 6² + 7² = 36 + 49 = 85 ≠ 100 = 10²), but we don't need to verify that since all sides are provided.
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4. Trapezoid
- Top base = 5 cm
- Bottom base = 8 cm
- Left side = 6 cm
- Right side = 6 cm
Add all sides:
Perimeter = 5 + 8 + 6 + 6 =
25 cm
✔ Answer: 25 cm
---
5. Pentagon
- All five sides are labeled as
12 cm
So it’s a regular pentagon (all sides equal).
Perimeter = 5 × 12 =
60 cm
✔ Answer: 60 cm
---
✔ Final Answers:
1.
Rectangle:
38 cm
2.
Square:
320 mm
3.
Triangle:
23 cm
4.
Trapezoid:
25 cm
5.
Pentagon:
60 cm
> 🔔 Remember: Always include units! And perimeter is the sum of all side lengths.
Parent Tip: Review the logic above to help your child master the concept of perimeter worksheet for middle school.
