Practice Questions
Concept Explanation
Perimeter is the total distance around a closed 2D figure (linear units). For circles, perimeter is called circumference.
Formulas
- Square: 4a; Rectangle: 2(l + b)
- Triangle: sum of three sides
- Circle: 2πr (π = 22/7)
- Semicircle: πr + 2r
Example
Rectangle 12 cm × 5 cm: perimeter = 2(12 + 5) = 34 cm.
Common Trap
Do not confuse perimeter with area. Fencing/wiring problems usually need perimeter or circumference.
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Q1 EasyTriangle sides 5, 12, 13 cm. Perimeter:Explanation5 + 12 + 13 = 30 cm. Hence the answer is 30 cm.
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Q2 EasyPerimeter of a square of side 9 cm is:ExplanationPerimeter = 4 × 9 = 36 cm. Hence the answer is 36 cm.
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Q3 EasySquare perimeter 48 cm. Side is:ExplanationSide = 48/4 = 12 cm. Hence the answer is 12 cm.
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Q4 EasyCircumference of circle radius 7 cm (π = 22/7) is:ExplanationC = 2πr = 44 cm. Hence the answer is 44 cm.
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Q5 EasyPerimeter of rectangle 15 cm × 8 cm is:ExplanationP = 2(15 + 8) = 46 cm. Hence the answer is 46 cm.
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Q6 EasyRectangle perimeter 50 cm, length 15 cm. Breadth:Explanation2(15 + b) = 50, b = 10 cm. Hence the answer is 10 cm.
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Q7 EasyRegular pentagon side 7 cm. Perimeter:Explanation5 × 7 = 35 cm. Hence the answer is 35 cm.
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Q8 EasyAn equilateral triangle has side 12 cm. Perimeter is:ExplanationP = 3 × 12 = 36 cm. Hence the answer is 36 cm.
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Q9 EasyIsosceles triangle equal sides 10 cm, base 12 cm. Perimeter:Explanation10 + 10 + 12 = 32 cm. Hence the answer is 32 cm.
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Q10 MediumCircumference 132 cm (π = 22/7). Radius:Explanation2πr = 132, r = 132 × 7 / 44 = 21 cm. Hence the answer is 21 cm.
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Q11 MediumRope around circular park r = 14 m (π = 22/7). Rope length:ExplanationCircumference = 88 m. Hence the answer is 88 m.
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Q12 MediumSquare and equilateral triangle have equal perimeter 36 cm. Triangle side:ExplanationTriangle side = 36/3 = 12 cm. Hence the answer is 12 cm.
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Q13 MediumWire forms square of area 121 sq cm. Length of wire is:ExplanationSide = 11 cm. Wire = perimeter = 44 cm. Hence the answer is 44 cm.
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Q14 MediumSemicircle diameter 14 cm (π = 22/7). Perimeter of shape is:ExplanationArc = πr = 22 cm; plus diameter 14 cm; total 36 cm. Hence the answer is 36 cm.
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DS1 Easy
What is the perimeter of the rectangle?
Statement ILength is 15 cm and breadth is 8 cm.
Statement IIArea is 120 sq cm and length is 15 cm.
ExplanationStatement I: P = 46 cm. Statement II: breadth = 8, P = 46 cm. Each alone sufficient. Answer: D. -
DS2 Easy
What is the perimeter of the square?
Statement IArea is 144 sq cm.
Statement IIDiagonal is 12√2 cm.
ExplanationEach gives side 12 cm, perimeter 48 cm. Answer: D.
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DS3 Medium
What is the circumference of the circle? (π = 22/7)
Statement IRadius is 21 cm.
Statement IIArea is 1386 sq cm.
ExplanationStatement I: C = 132 cm. Statement II: r = 21, C = 132 cm. Each alone sufficient. Answer: D. -
DS4 Medium
What is the perimeter of the triangle?
Statement ISides are 7 cm, 24 cm and 25 cm.
Statement IIIt is a right triangle with legs 7 cm and 24 cm.
ExplanationEach gives third side 25 cm, perimeter 56 cm. Answer: D.