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Published on: 18/09/2019
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1.
A cylindrical pillar is 50 cm in diameter and 3.5 cm in height.Find the cost of painting the curved surface of the piller at the rate of Rs 10 per sq m.
2.
A cuboid is of dimensions 60 cm\(\times\)54 cm\(\times\)30 cm. How many small cubes with side 6 cm can be placed in the given cuboid?
3.
Find the height of a cuboid whose base area is 180 cm2 and volume is 900 cm3
4.
Find the volume of the following cylinders: Given, radius = 7 cm, height = 10 cm
5.
Find the volume of the following cubes : with a side 1.5 m.
6.
Four horses are tethered with equal ropes at 4 corners of a square field of side 70 m, so that they just can reach one another.Find the area left ungrazed by the horses.
7.
After the surface area of a cube is painted, the cube is cut into 64 smaller cubes of sane dimensions (see the figure). How many have no face painted? 1 face painted?
8.
Find the total surface area of the following cuboid
9.
Find the area of the following fields,All dimensions are in metres,
10.
The area of a trapezium is 34 cm2 and the length of one of the parallel sides is 10 cm and its height is 4 cm. Find the length of the other parallel side.
11.
Parallelogram is divided into two congruent triangles by drawing a diagonal across it. Can we divide a trapezium into two congruent triangles?
12.
Find the area of the polygon ABCD, if AD= 10 cm, AS= 7 cm and AP=2 cm
13.
Find the area of a rhombus, whose diagonals are of lengths 20 cm and 15 cm.
14.
The ratio of the length and breadth of a rectangle is 5 : 3. If length is 8 m more than breadth, then find the area of the rectangle.
15.
The length of a rectangular field is 100 m and its breadth is 40 m. What will be the area of the field?
1.
Rs 55
2.
Given, dimensions of cuboid are 60 cm\(\times\)54 cm\(\times\)30 cm
i.e.length= 60 cm, breadth = 54 cm and height = 30 cm
∴ Volume of the cuboid = l \(\times\)b \(\times\)h = 60\(\times\)54 \(\times\)30
= (60\(\times\)54\(\times\)30)cm3
Also,givenside of a small cube = 6 cm
∴ Volume of one cube = a3 = (6)3 = (6\(\times\)6 \(\times\)6) cm3
Here,small cubes are placed in cuboid, required number of smallcubes
=\(\frac { Volume\ of\ cuboid }{ Volume\ of\ one\ cube } =\frac { 60\times 54\times 30 }{ 6\times 6\times 6 } \) = 450
3.
Given,base area of cuboid = 180 cm2
and volume of cuboid = 900 cm3
We know that, volume of cuboid = Base area\(\times\) Height
⇒ 900 = 180 Heigth ⇒ Height = \(\frac { 900 }{ 180 } \)=5 cm
Hence,height of the cuboid is 5 cm.
4.
∴ VoIume of the cylinder = \({ \pi r }^{ 2 }h=\frac { 22 }{ 7 } \times 7\times 7\times 10\)=1540 cm3
5.
Given, side of cube = 1.5 cm
∴ Volume of the cube = 1.5 =l3 = (1.5)3 = 1.5\(\times\)1.5\(\times\)1.5 = 3.375 m3
6.
1050 m2
7.
In the given figure, we have 24 cubes, which have 1 face painted.
8.
Given,length (1)= 4 cm, breadth (b) = 4 cm and and height (h) = 10 cm
∴ Total surface area of the cuboid = 2(lb+ bh + hl)
2(4\(\times\)4+4\(\times\)10+10\(\times\)4) = 2(16 + 40 + 40) = 2 \(\times\)96 = 192 cm2
9.
30100 m2
10.
Given, area of trapezium = 34 cm2
and height of trapezium = 4 cm
Let length of one parallel side be x cm, then another parallel side is 10 cm.
Now, area of trapezium =\(\frac { 1 }{ 2 } \times \) sum of parellel sides\(\times\)Perpendicular distance between the parallel sides
⇒ 34 =\(\frac { 1 }{ 2 } \times \) (x+10) \(\times\)4 ⇒ 34 =2x(x+10)
⇒ 17 = x + 10
⇒ x = 17-10 = 7
Hence, the length of other parallel side is 7 cm
11.
In a parallelogram, opposite sides are parallel and equal, so by drawing a diagonal, it can be divided into two congruent triangle but in a trapezium, only one pair of opposite sides is parallel, so it cannot be divided into two congruent triangles
12.
Area of polygon ABCD = Area of ΔABP +Area of trapezium BCSP+Area of ΔCDS
= \(\frac { 1 }{ 2 } \)\(\times\)AP \(\times\)PB + PS \(\times\)(PB+SC)+ SD\(\times\) SC
= \(\frac { 1 }{ 2 } \)\(\times\)2\(\times\) 2+\(\frac { 1 }{ 2 } \)\(\times\)5 (2+3)+ 3\(\times\) 3
=2 +12.5+4.5 = 19cm2
Hence the area of polygon ABCD is 19 cm2
13.
We have d1 =20cm d2 =15 cm
Area of rhombus =\(\frac { 1 }{ 2 } \) \(\times\)d1 \(\times\)d2 = \(\frac { 1 }{ 2 } \)\(\times\)20 \(\times\)15 = \(\frac { 1 }{ 2 } \)\(\times\)300 = 150 cm2
Hence, the area of rhombus 150 cm2
14.
240 m2
15.
400 m2
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