Question:
What is the perimeter of a square with side 7 cm?
What is the perimeter of a square with side 7 cm?
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For square perimeter, multiply side by 4.
Updated On: Aug 11, 2025
- 24 cm
- 28 cm
- 32 cm
- 36 cm
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Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Given
- Shape: Square (all four sides equal; all angles 90°)
- Side length: a = 7 cm
- Asked: Perimeter (total boundary length)
Concepts & Formulae
- Definition of Perimeter: The perimeter of any polygon is the sum of the lengths of all its sides.
- Square property: A square has 4 congruent (equal) sides. If each side is a, then the sides are: a, a, a, a.
-
Derivation of the formula:
Perimeter P = a + a + a + a = 4a. (No area involved here.)
Step-by-step Computation
- Write the formula: P = 4a
- Substitute the given side: a = 7 cm ⇒ P = 4 × 7 cm
- Multiply: 4 × 7 = 28
- Attach correct units: Perimeter is a length ⇒ P = 28 cm
Checks & Validation
- Repeated addition check: 7 + 7 + 7 + 7 = 28 cm ✓
- Units check: Input in centimeters → output in centimeters ✓
- Reasonableness check: Since one side is 7 cm, four sides should be a bit under 30 cm; 28 cm is sensible ✓
Common Mistakes to Avoid
- Using area formula a² (49 cm²) instead of perimeter – that gives area, not perimeter.
- Forgetting to multiply by 4 (using just a = 7 cm).
- Dropping units (always report length in cm here).
Final Answer
28 cm — this matches the correct option.
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