<\/span><\/h2>\nQuestion 1.
If two cubes of side 6 cm are joined face to face, then find the volume of the resulting cuboid.
Solution:
Side of a cube = 6 cm
\u2234 By joining two such cubes, the length of so
formed cuboid (l) = 6 x 2 = 12 cm
Breadth (b) = 6 cm
Height (h) = 6 cm
\u2234 Volume = lbh = 12 x 6 x 6 cm3<\/sup>
= 432 cm3<\/sup><\/p>\nQuestion 2.
Three cubes of metal whose edges are in the ratio 3 : 4 : 5, are melted down into a single cube whose diagonals is 12\u00a03<\/span><\/span>\u2013\u221a<\/span><\/span><\/span><\/span>\u00a0cm. Find the edges of three cubes.
Solution:
Ratio in the sides of three cubes = 3 : 4 : 5
Let side of first cube = 3x
and side of second cube = 4x
and side of third cube = 5x
\u2234 Sum of volume of three cubes
= (3x)3<\/sup>\u00a0+ (4x)3<\/sup>\u00a0+ (5x)3<\/sup>
= 27x3<\/sup>\u00a0+ 64x3<\/sup>\u00a0+ 125x3<\/sup>\u00a0= 216x3<\/sup>
\u2234 Volume of the cube formed Jby melting these three cubes = 216x3<\/sup>
![\"RD](\"https:\/\/farm2.staticflickr.com\/1945\/44732596225_3ec7c64aa6_o.png\")
![\"Surface](\"https:\/\/farm2.staticflickr.com\/1950\/44921829714_23b6f2abb8_o.png\")
\u2234 Side of first cube = 3x = 3 x 2 = 6 cm
Side of second cube = 4x = 4\u00d72 = 8 cm
and side of third cube = 5.r = 5 x 2 = 10 cm<\/p>\nQuestion 3.
If the perimeter of each face of a cube is 32 cm, find its lateral surface area. Note that four faces which meet the base of a cube are called its lateral faces.
Solution:
Perimeter of each face of a cube = 32 cm
\u2234 Length of edge =\u00a032<\/span>4<\/span><\/span><\/span><\/span><\/span>\u00a0= 8 cm
and lateral surface area of the cube = 4 x (side)2<\/sup>
= 4 x 8 x 8 = 256 cm2<\/sup><\/p>\nQuestion 4.
Find the edge of a cube whose surface area is 432 m2<\/sup>.
Solution:
![\"RD](\"https:\/\/farm2.staticflickr.com\/1954\/44732596055_819443a57b_o.png\")
<\/p>\nQuestion 5.
A cuboid has total surface area of 372 cm2<\/sup>\u00a0and its lateral surface area is 180 cm2<\/sup>, find the area of its base.
Solution:
Total surface area of a cuboid = 372 cm2<\/sup>
and lateral surface area = 180 cm2<\/sup>
\u2234 Area of base and roof = 372 \u2013 180 = 192 cm2<\/sup>
and area of base =\u00a0192<\/span>2<\/span><\/span><\/span><\/span><\/span>\u00a0= 96 cm2<\/sup><\/p>\nQuestion 6.
Three cubes of each side 4 cm are joined end to end. Find the surface area of the resulting cuboid.
Solution:
By joining three cubes of side 4 cm each, end is end, we get a cuboid
Length of cuboid = 4 x 3 = 12 cm
Breadth = 4 cm
and height = 4 cm
![\"Class](\"https:\/\/farm2.staticflickr.com\/1926\/44921829574_e7fbb0ab9b_o.png\")
\u2234 Surface area = 2(lb + bh + hl)
= 2[12 x4+4\u00d74 + 4x 12] cm2<\/sup>
= 2[48 + 16 + 48] cm2<\/sup>
= 2 x 112 = 224 cm2<\/sup><\/p>\nQuestion 7.
The surface area of a cuboid is 1300 cm2. If its breadth is 10 cm and height is 20 cm, find its length.
Solution:
Surface area of a cuboid = 1300 cm2<\/sup>
Breadth (b) = 10 cm
and height (h) = 20 cm
Let l be the length, then
= 2 (lb + bh + hl) = 1300
lb+ bh + hl =\u00a01300<\/span>2<\/span><\/span><\/span><\/span><\/span>\u00a0= 650
l x 10 + 10 x 20 + 20 x l = 650
10l + 20l + 200 = 650
\u21d2 30l = 650 \u2013 200 = 450
\u21d2 l =\u00a0450<\/span>30<\/span><\/span><\/span><\/span><\/span>\u00a0= 15
\u2234 Length of cuboid = 15 cm<\/p>\nWe have included all the information regarding CBSE<\/a> RD Sharma Class 9 Solutions Chapter 18 VSAQS. If you have any query feel free to ask in the comment section.\u00a0<\/span><\/p>\n
![\"RD](\"https:\/\/www.kopykitab.com\/blog\/wp-content\/uploads\/2021\/09\/RD-Sharma-Class-9-Solutions-Chapter-18-VSAQS.jpg\")
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