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प्रश्न
The fencing of a square garden is 20 m in length. How long is one side of the garden?
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उत्तर
Given perimeter of garden = 20 m which has to be fenced.
Length of one side
= perimeter/4
= 20 + 4
= 5 m
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संबंधित प्रश्न
The principle of ‘parallax’ in section 2.3.1 is used in the determination of distances of very distant stars. The baseline AB is the line joining the Earth’s two locations six months apart in its orbit around the Sun. That is, the baseline is about the diameter of the Earth’s orbit ≈ 3 × 1011m. However, even the nearest stars are so distant that with such a long baseline, they show parallax only of the order of 1” (second) of arc or so. A parsec is a convenient unit of length on the astronomical scale. It is the distance of an object that will show a parallax of 1” (second) of arc from opposite ends of a baseline equal to the distance from the Earth to the Sun. How much is a parsec in terms of meters?
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Reason (R): The distance travelled by the light in one year is one light year.
Guess the lengths to draw these things. Ask your friend to draw the same. After you make the drawing use a scale to measure the length. Whose drawing showed a better guess?
| Guess its length and draw |
Measure of your drawing |
Measure of your friend’s drawing |
| An ant of length less than 1 cm |
||
| Pencil of length about 7 cm |
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| A glass 11 cm high with water up to 5 cm |
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| A bangle of perimeter 20 cm |
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| A curly hair of length 16 cm |
Which line is longer? C or D? Measure each line. How good is your guess?

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| Size of | Your guess in cm | Your measure in cm | ||
| Length | Width | Length | Width | |
| 100 Rupee note | ||||
| 10 Rupee note | ||||
| 20 Rupee note | ||||
| 5 Rupee note | ||||
| Post card | ||||
| Math-Magic book | ||||
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- A
Gold wire for A = _________ metres - B

Gold wire for B = _________ metres - C
Gold wire for C = __________ metres
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- D

So he will get __________ metres of gold wire!!
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- What is the length of the boundary of lake B in the drawing?
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- A longer boundary around the lake will help more birds to lay their eggs. So which lake should be kept for birds? Which lake should be used for boats?
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What is the unit of measurements of very small lengths?
SI unit of electric current is ______.
How many astronomical units (A.U.) make 1 parsec?
What is an Astronomical Unit (AU)?
