Mensuration
- The perimeter and length of a rectangle are 40 m and 12 m respectively. Its breadth will be
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Using Rule 9,
Perimeter of rectangle = 40 metre
Length = 12 metre
∴ 2(l + b) = 40
⇒ 2 (12 + b) = 40⇒ 12 + b = 40 = 20 2
⇒ b = 20 – 12 = 8 metreCorrect Option: B
Using Rule 9,
Perimeter of rectangle = 40 metre
Length = 12 metre
∴ 2(l + b) = 40
⇒ 2 (12 + b) = 40⇒ 12 + b = 40 = 20 2
⇒ b = 20 – 12 = 8 metre
- If the perimeter of a square and a rectangle are the same, then the area P and Q enclosed by them would satisfy the condition
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Using Rule 10,
Let the side of square be 1 cm, then 2 (l + b)
= 4 × side = 4 × 1
⇒ l + b = 2, If l = 1.5, b = 0.5
∴ Area of square = 1 sq.cm.
and Area of rectangle = 1.5 × 0.5 = 0.75 sq.cm.
For a given perimeter, square has the largest area. i.e, P > QCorrect Option: C
Using Rule 10,
Let the side of square be 1 cm, then 2 (l + b)
= 4 × side = 4 × 1
⇒ l + b = 2, If l = 1.5, b = 0.5
∴ Area of square = 1 sq.cm.
and Area of rectangle = 1.5 × 0.5 = 0.75 sq.cm.
For a given perimeter, square has the largest area. i.e, P > Q
- PQRS is a square with side 10 cm. A, B, C and D are mid–points of PQ, QR, RS and SP respectively. Then the perimeter of the square ABCD so formed is
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PA = AQ = QB = 5 cm.
∴ ∠AQB = 90°
∴ AB = √AQ² + QB²
= √5² + 5² = √25 + 25
= √50 = 5√2 cm.
∴ Perimeter of ABCD = 4 × 5√2 = 20√2 cm.Correct Option: B
PA = AQ = QB = 5 cm.
∴ ∠AQB = 90°
∴ AB = √AQ² + QB²
= √5² + 5² = √25 + 25
= √50 = 5√2 cm.
∴ Perimeter of ABCD = 4 × 5√2 = 20√2 cm.
- A piece of wire when bent to form a circle will have a radius of 84 cm. If the wire is bent to form a square, the length of a side of the square is
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Using Rule 14,
Length of wire = Circumference of circle = 2πr= 2 × 22 × 84 = 528 cm. 2
∴ Perimeter of square = 528 cm.
⇒ 4 × side = 528⇒ Side = 528 = 132 cm. 4
Correct Option: B
Using Rule 14,
Length of wire = Circumference of circle = 2πr= 2 × 22 × 84 = 528 cm. 2
∴ Perimeter of square = 528 cm.
⇒ 4 × side = 528⇒ Side = 528 = 132 cm. 4
- The perimeters of two similar triangles are 30 cm and 20 cm respectively. If one side of the first triangle is 9 cm. Determine the corresponding side of the second triangle.
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If the required side be x cm, then
30 = 9 20 x
⇒ 3x = 9 × 2⇒ x = 9 × 2 = 6 cm. 3 Correct Option: B
If the required side be x cm, then
30 = 9 20 x
⇒ 3x = 9 × 2⇒ x = 9 × 2 = 6 cm. 3