Read the following information carefully and answer the questions bas...
Length of the cube = 2x - 8
⇒ Lateral surface area of the cube = 4a2 = 4(2x - 8)2 = 4(4x2 + 64 - 32x)
⇒ 4(4x2 + 64 - 32x) = 4y (z - 4) ---------- (1)
Radius of cylinder = x
Height of cylinder = (z - 3)
Volume of the cylinder = π * x2 *(z - 3)
If the dimensions were reversed = π*(z - 3)2*x
Thus, π*(z - 3)2*x = 3/2* π*x2*(z - 3)
⇒ z - 3 = 3/2*x
⇒ z = (3x/2) + 3
Now, radius of sphere = y + 1 cm
Volume of sphere = 4π/3*(y + 1)3
Radius of smaller sphere = x/2
Volume of smaller sphere = 4π/3*(x/2)3
⇒ 4π/3*(y + 1)3 = 27*4 π/3*(x/2)3
⇒ y + 1 = 3(x/2) = 3x/2
⇒ y = (3x/2) -1
From equation (1) we get
4(4x2 + 64-32x) = 4y (z - 4) = 4(3x/2 - 1)(3x/2 + 3 - 4) = (3x - 2)2
⇒ 16x2 + 256 - 128x = 9x2 + 4 - 12x
⇒ 7x2 - 116x + 252 = 0
⇒ (x - 14)(7x - 18) = 0
⇒ x = 14 or x = 18/7
So, z = 3x/2+3 = 24 or 48/7
And, y = 3x/2-1 = 20 or 20/7. But y + 1 = 27/7< />
Thus, y = 20, x = 14 and z = 24
Now, length of cuboid = x + y = 14 + 20 = 34 cm
Breadth of cuboid = y + z = 20 + 24 = 44 cm
Volume of cuboid = 5xyz - 688 = 5*14*20*24 - 688 = 32912 cubic cm
Height of cuboid = 32912/34/44 = 22cm
Thus,
For cube, edge = 2x - 8 = 2*14 - 8 = 20 cm
For cuboid, length = 34 cm, breadth = 44 cm, heigh t= 22 cm
For cylinder, radius=14 cm, height = 24 - 3 = 21 cm
For smaller sphere, radius = 7 cm
For larger sphere, radius = 21 cm
For A, we have
Lateral surface area of the surface = xy + 3x + z2 + 12y + 62
= 14*20 + 3*14 + 242 + 12*20 + 62 =1200
⇒ 4*area of base = 1200
⇒ Area of base = 300 sq cm
⇒ Total surface area of the cube=6*area of base=6*300=1800 sq cm
For B, we have
Radius of hemisphere = (x+y+z+5)/3= (14+20+24+5)/3 = 21 cm
Total surface area of the hemisphere=3 π*21*21 = 4158 sq cm
For C, we have
Radius of the cone= y2/(2x-12)=20*20/(28-12) = 25 cm
Height of the cone = z + 1 = 25 cm
⇒ Slant height of the cone=√(252 +252) = 25√2 cm
Total Surface area of the cone = π*radius2 + π*radius*slant height = π*252+ π*25*25√2 = 1964.28+2777.919 = 4742.204 sq cm
For D, we have
Radius of cylinder = 3x - z = 3*14 - 24 = 18 cm
Volume of the cylinder = z3 + y3 - 440 = 243 + 203 - 440 = 21384 cubic cm
Area of base = π*18*18 = 324 π sq cm
Height of the cylinder = Volume of the cylinder/Area of base = 21384/324 π = 21 cm
⇒ Total surface area of the cylinder = 2*area of base +2 π*radius*height = 2 π*182 + 2 π*18*21 = 2036.57 + 2376 = 4412.57 sq cm
Thus, total surface area of the cone is maximum