Mensuration
- The area of a circle inscribed in a square of area 2m² is
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Using Rule 10 and 14,
Side of square = √2 metre Radius of in-circle= √2 = 1 metre 2 √2
Area of the circle = πr²= π × 1 = π sq. metre 2 2 Correct Option: B
Using Rule 10 and 14,
Side of square = √2 metre Radius of in-circle= √2 = 1 metre 2 √2
Area of the circle = πr²= π × 1 = π sq. metre 2 2
- Three coins of the same size (radius 1 cm) are placed on a table such that each of them touches the other two. The area enclosed by the coins is
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Using Rule 6 AND 17,
Obviously, the triangle ABC will be equilateral.
AB = BC = CA = 2 cm.
Area of ∆ ABC= √3 × 2 × 2 4
= √3 cm²
Then, area ‘A’ of the three sectors each of angle 60° in a circle of radius 1 cm.A = 3 × 60 × π × 1 = π 360 2
∴ Area of the shaded portion= √3 - π cm². 2 Correct Option: B
Using Rule 6 AND 17,
Obviously, the triangle ABC will be equilateral.
AB = BC = CA = 2 cm.
Area of ∆ ABC= √3 × 2 × 2 4
= √3 cm²
Then, area ‘A’ of the three sectors each of angle 60° in a circle of radius 1 cm.A = 3 × 60 × π × 1 = π 360 2
∴ Area of the shaded portion= √3 - π cm². 2
- Each side of a regular hexagon is 1 cm. The area of the hexagon is
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Area of regular hexagon = 3√3 × (side)² 2 = 3√3 × 1 = 3√3 cm² 2 2 Correct Option: A
Area of regular hexagon = 3√3 × (side)² 2 = 3√3 × 1 = 3√3 cm² 2 2
- An equilateral triangle of side 6 cm has its corners cut off to form a regular hexagon. Area (in cm2) of this regular hexagon will be
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Tricky approach
Side of the regular hexagon = 1 × 6 = 2cm 3 ∴ Area of the hexagon = 3√3 a² 2 ∴ Area of the hexagon = 3√3 × 2 × 2 = 6√3 sq. cm. 2 Correct Option: C
Tricky approach
Side of the regular hexagon = 1 × 6 = 2cm 3 ∴ Area of the hexagon = 3√3 a² 2 ∴ Area of the hexagon = 3√3 × 2 × 2 = 6√3 sq. cm. 2
- The ratio of the area of a regular hexagon and an equilateral triangle having same perimeter is
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Perimeter of regular hexagon = Perimeter of equilateral triangle.
i.e. If a side of the regular hexagon be x units, then side of triangle = 2x units.∴ Required ratio = 6 √3 x² : √3 (2x)² 4 4
= 6 : 4 = 3 : 2Correct Option: C
Perimeter of regular hexagon = Perimeter of equilateral triangle.
i.e. If a side of the regular hexagon be x units, then side of triangle = 2x units.∴ Required ratio = 6 √3 x² : √3 (2x)² 4 4
= 6 : 4 = 3 : 2