Question
The radius and height of a right circular cone are in
the ratio 3: 4. If its curved surface area (in cm²) is 240 π, then its volume (in cm³) is:Solution
Curved surface area of cone = π r l Volume of cone = (1/3) π r2 h Slant height = √(h2 + r2 ) Let the radius and height of the cone be 3x and 4x Slant height = √[(4x)2 + (3x)2 ] ⇒ √(16x2 + 9x2 ) ⇒ √25x ⇒ 5x Curved suface area = π × 3x × 5x2 ⇒ 240 π = π × 15x ⇒ x2 = 16 ⇒ x = 4 Radius = 12 cm Height = 16 cm Slant height = 20 cm Volume of the cone = (1/3) × π × 144 × 16 ⇒ 48 × 16 × π ⇒ 768 π
7, 14, 42, 210, 1470, ?
A sequence {Vₙ} is defined for n ≥ 1 by:
I) For every n ≥ 3: Vₙ = 2Vₙ₋₁ − Vₙ₋₂ + 4
It is known that - V₃ = 22 and ...
12, 20, 36, ?, 132, 260
If 6 4 x 5.75 9,
Then, (x²-1) = ?
...12 13 30 �...
112 162 199 ? 242 252
...21 11.5 13 ? 45.5 116.75
...171, 173, 183, 213 , ‘?’, 411, 633.
114 106 102 100 99 ?
...Choose the correct alternative
21: 3 ∷ 574: ?
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