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Question

Which of the four options provided below will be the closest to the area of an equilateral triangle, each of whose sides is 10 m long?

This question was previously asked in
RRB NTPC 2019 CBT 1 Question Paper (8-Mar-2021) (Shift 2)
The correct answer is
$43.25\text{ m}^2$

Finding Equilateral Triangle Area

The problem asks for the area of an equilateral triangle with a side length of 10 m.

Equilateral Triangle Area Formula

The area ($A$) of an equilateral triangle with side length ($s$) is given by the formula:

$ A = \frac{\sqrt{3}}{4} s^2 $

Calculating the Area

Given the side length $s = 10$ m, substitute this value into the formula:

  • $ A = \frac{\sqrt{3}}{4} (10 \text{ m})^2 $
  • $ A = \frac{\sqrt{3}}{4} \times 100 \text{ m}^2 $
  • $ A = 25\sqrt{3} \text{ m}^2 $

Approximating the Value

Using the approximate value of $ \sqrt{3} \approx 1.732 $:

  • $ A \approx 25 \times 1.732 \text{ m}^2 $
  • $ A \approx 43.30 \text{ m}^2 $

Comparing with Options

Now, compare the calculated area ($ \approx 43.30 \text{ m}^2 $) with the given options:

  • Option 1: $42.25\text{ m}^2$
  • Option 2: $45.25\text{ m}^2$
  • Option 3: $43.25\text{ m}^2$
  • Option 4: $44.25\text{ m}^2$

The calculated area, $43.30 \text{ m}^2$, is closest to Option 3, $43.25 \text{ m}^2$.

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Similar Questions

  1. The ratio of the length to the breath of a rectangular field is $6 : 5$. If the breath is 25 m less than the length, the perimeter of the field is:
  2. The ratio of the area of an equilateral triangle of side $x$ to the area of a square of side $x$ is:
  3. Find the perimeter of a semicircle with a radius of 7 cm. (Use $\pi = \frac{22}{7}$)
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Important Questions from 2-D Mensuration

  1. The sides of a rectangular field are 169 m and 154 m long. Its area is equal to the area of a circular field. What is the circumference (in m) of the circular field? Take $\pi = \frac{22}{7}$
  2. Find the area of a sector with a central angle of 150° in a circle with a radius of 12 cm.
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