- A16 cm
- B56 cm
- C63 cm
- D70 cm
Step-by-Step Solution
For a regular polygon, = number of sides × side length = cm. 56 cm and 70 cm come from using 8 or 10 sides by mistake; 16 cm comes from adding 9 + 7 instead of multiplying.
Answer: C) 63 cm
A regular polygon has 9 equal sides, each 7 cm long. Find its perimeter.
Class 6MensurationMensuration
Key idea: Perimeter shortcuts for special shapes
**Rectangle**: opposite sides are equal, so perimeter = l + b + l + b = 2(l + b).
**Square**: all four sides equal, so perimeter = 4 × s.
**Equilateral triangle**: all three sides equal, perimeter = 3 × s.
**Regular polygon with n sides of length s**: perimeter = n × s.
These shortcuts are just 'add the sides' written shorter.
**Square**: all four sides equal, so perimeter = 4 × s.
**Equilateral triangle**: all three sides equal, perimeter = 3 × s.
**Regular polygon with n sides of length s**: perimeter = n × s.
These shortcuts are just 'add the sides' written shorter.
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