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Sunita stitches a lace border right around a five-sided table mat whose sides measure 12 cm, 8 cm, 15 cm, 9 cm and 6 cm. What length of lace does she need?

Class 6MensurationMensuration
  • A50 cm
  • B44 cm
  • C60 cm
  • D100 cm

Step-by-Step Solution

Perimeter means adding every side exactly once: 12 + 8 + 15 + 9 + 6 = 50 cm. The trap is 44 cm — that is what you get if the last 6 cm side is skipped while going around. 60 cm assumes all five sides are 12 cm, which they are not.
Answer: A) 50 cm

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.

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