Home
Class 9
MATHS
Write True or False and justify your ans...

Write True or False and justify your answer:
The cost of levelling the ground in the form of a triangle having the sides `51` `m`, `37` `m` and `20` `m` at the rate of `Rs` `3` per `m^(2)` is `Rs` `918`.

Text Solution

AI Generated Solution

The correct Answer is:
To determine whether the statement is true or false, we need to calculate the area of the triangular ground with sides 51 m, 37 m, and 20 m using Heron's formula, and then find the cost of leveling the ground at the rate of Rs 3 per m². ### Step-by-step Solution: 1. **Identify the sides of the triangle:** - Let \( a = 51 \, m \) - Let \( b = 37 \, m \) - Let \( c = 20 \, m \) 2. **Calculate the semi-perimeter (s):** \[ s = \frac{a + b + c}{2} = \frac{51 + 37 + 20}{2} = \frac{108}{2} = 54 \, m \] 3. **Apply Heron's formula to find the area (A):** \[ A = \sqrt{s(s-a)(s-b)(s-c)} \] Substituting the values: \[ A = \sqrt{54(54 - 51)(54 - 37)(54 - 20)} \] \[ = \sqrt{54 \times 3 \times 17 \times 34} \] 4. **Simplify the expression under the square root:** - First, calculate \( 54 \times 3 = 162 \) - Then, calculate \( 17 \times 34 = 578 \) - Now, calculate \( 162 \times 578 \) To simplify: \[ 162 = 9 \times 18 \quad \text{and} \quad 578 = 17 \times 34 \] Thus, \[ A = \sqrt{54 \times 3 \times 17 \times 34} = \sqrt{(9 \times 6) \times 3 \times (17 \times 34)} \] This can be further simplified to: \[ A = \sqrt{(9 \times 17) \times (6 \times 34)} = \sqrt{153 \times 204} \] 5. **Calculate the area:** After performing the calculations, we find: \[ A \approx 306 \, m^2 \] 6. **Calculate the cost of leveling the ground:** \[ \text{Cost} = \text{Area} \times \text{Cost per m}^2 = 306 \, m^2 \times 3 \, \text{Rs/m}^2 \] \[ = 918 \, Rs \] 7. **Conclusion:** Since the calculated cost of leveling the ground is Rs 918, which matches the statement given in the question, we conclude that the statement is **True**.

To determine whether the statement is true or false, we need to calculate the area of the triangular ground with sides 51 m, 37 m, and 20 m using Heron's formula, and then find the cost of leveling the ground at the rate of Rs 3 per m². ### Step-by-step Solution: 1. **Identify the sides of the triangle:** - Let \( a = 51 \, m \) - Let \( b = 37 \, m \) - Let \( c = 20 \, m \) ...
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • HERON'S FORMULA

    NCERT EXEMPLAR ENGLISH|Exercise Short Answer Type Questions|10 Videos
  • HERON'S FORMULA

    NCERT EXEMPLAR ENGLISH|Exercise Long Answer Type Questions|8 Videos
  • HERON'S FORMULA

    NCERT EXEMPLAR ENGLISH|Exercise Long Answer Type Questions|8 Videos
  • COORDINATE GEOMETRY

    NCERT EXEMPLAR ENGLISH|Exercise Exercise 3.4 Long Answer Type Questions|5 Videos
  • INTRODUCTION TO EUCLID GEOMETRY

    NCERT EXEMPLAR ENGLISH|Exercise Exercise 5.4 Long Answer Type Questions|5 Videos

Similar Questions

Explore conceptually related problems

Find the cost of fencing a triangular garden with sides 20m, 24 m and 32 m at the rate of 142 per metre.

Write True or False and justify your answer: The area of regular hexagon of side a is the sum of the areas of the five equilateral triangles with side a.

Find the cost of laying grass in a triangular field of sides 50 m , 65 m and 65 m at the rate of rupee 7 per m^(2) .

Find the cost of fencing a rectangular park of length 250 m andbreadth 175 m at the rate of Rs 12 per metre.

Find the cost of fencing a rectangular park of length 175m and breadth 125m at the rate of Rs. 12 per meter.

What is the cost of tiling a rectangular plot of land 500 m long and 200 m wide at the rate of Rs 8 per hundred sq m.?

Find the cost of levelling a field measuring 75 m by 60 m at the rate of Rs 8 per sq. m .

The dome of a building is in the form of a hemisphere. Its radius is 63m. Find the cost of painting it at the rate of Rs. 2 per sq.m.

Write True or False and justify your answer: In a triangle, the sides are given as 11 cm , 12 cm and 13 cm . The length of the altitude is 10.25 cm corresponding to the side having 12 cm.

One side of a square plot is 250m, find the cost of levelling it at the rate of Rs. 2 per square metre.