Question

In the marriage of Raj’s brother Rajesh, a conical tent is made by stitching 12 triangular pieces of cloth of two different colors red and white alternately, each piece measuring 10 cm, 20 cm and 20 cm.
d. How much cloth of red colour is required to make a conical tent? (i) 125√15 cm2 (ii) 150√15 cm2 (iii) 165√15 cm2 (iv) 180√15 cm2​

Answer 1

Answer:

Correct Question

In the marriage of Raj’s brother Rajesh, a conical tent is made by stitching 12 triangular pieces of cloth of two different colors red and white alternately, each piece measuring 10 cm, 20 cm and 20 cm.

d. How much cloth of red colour is required to make a conical tent?

(a) 200 cm

(b) 300 cm

(c) 350 cm

(d) 400 cm

Step-by-step explanation:

Let us find the area of one of the triangular piece first .

For this , the sides are 10 cm , 20cm and 20 cm in length .

Semiperimeter -

> ( a + b + c )/2

> 25 cm .

> √s(s-a)(s-b)(s-c)

> √ 25 × ( 25 - 10)( 25 - 20)( 25 - 20)

> √ 25 × 15 × 5 × 5

> 25√15

The perimeter of the triangular piece -

> 10 cm + 20 cm + 20 cm

> 50 cm.

Perimeter of 6 pieces ( As there are two colours white and rec )

> 50 × 6

> 300 cm .

Hence Option (B) is the required answer .

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Answer 2

150√15cm^2

Step-by-step explanation:

semiperimeter = (a+b+c)/2

$s = (10+20+20)/2$

$s= 50 / 2$

$s=25$

$= √s(s-a)(s-b)(s-c)$

$=√25(25-10)(25-20)(25-20)$

 $= √25(15)(5)(5)$

$= √25*25*15$

$= 25√15$

As it is given the tent is made up of 12 pieces of clothes (6 pieces white and  6 pieces red)

$=6*25√15$

$=150√15$

And therefore the amount of red color cloth required is 150√15cm^2