Question

The sides of a triangular field are 7 m , 15m and 20 m . find the number of rose beds that can be prepared in the field , if each , rose bed, on an average needs 200 cm ^2 space.
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class 10th
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Answer 1

Given :-

The side of a triangular field are 7 m , 15m and 20 m .

To Find :-

Number of rose bed can be prepared

Answer

Area of triangle = a + b + c/2

Semiperimeter = 7 + 15 + 20/2

Semiperimeter = 42/2

Semiperimeter = 21 m

Now

Area = √s(s - a)(s - b)(s - c)

Area = √21(21 - 7)(21 - 15)(21 - 20)

Area = √21 × 14 × 6 × 1

Area = √1764

Area = 42 m²

Now

1 m² = 10,000 cm²

No. of rose bed may made = 42/200/10,000

No. of rose bed may made = 42/200 × 10000

No. of rose bed may made = 2100

Hope This Helps You ❤️

Answer 2

$\huge\bf\color{blue}{solution}$

When path built then the new radius

become = 42+3.5 = 45.5m

Now

Cost = Area×Rate

Let the old radius be 'r' and new radius be 'R'

Area of the garden

π(R² - r²)

22/7(45.5² - 42²)

22/7 × (2070.25 - 1764)

22/7 × 306.25

9625m.

Now

Cost = Rrea× Rate

Cost = 962.5×20

Cost = 19250