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Question

In a triangle $ABC$, the length of the side $AB$ is 2m, the angle at $C$ is $60^\circ$ and the angle at $B$ is $30^\circ$, what is the length of side $AC$?

This question was previously asked in
RRB ALP/Technician 2018 CBT 2 Electronics Mechanic Question Paper (23-Jan-2019) (Shift 1)
The correct answer is
$\frac{2}{\sqrt{3}}\text{ m}$

To find the length of side \(AC\) in triangle \(ABC\), we will employ the Law of Sines, which states:

\(\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}\)

From the question, we know:

  • The length of side \(AB = c = 2 \text{ m}\)
  • Angle at \(C = 60^\circ\)
  • Angle at \(B = 30^\circ\)

First, we calculate the angle at \(A\) using the angle sum property of triangles:

\(A = 180^\circ - C - B = 180^\circ - 60^\circ - 30^\circ = 90^\circ\)

Now, apply the Law of Sines:

\(\frac{AC}{\sin B} = \frac{AB}{\sin C}\)

Substitute known values:

\(\frac{AC}{\sin 30^\circ} = \frac{2}{\sin 60^\circ}\)

We know:

  • \(\sin 30^\circ = \frac{1}{2}\)
  • \(\sin 60^\circ = \frac{\sqrt{3}}{2}\)

Substituting these values gives:

\(\frac{AC}{\frac{1}{2}} = \frac{2}{\frac{\sqrt{3}}{2}}\)

Solving for \(AC\):

\(AC = \frac{2 \times \frac{1}{2}}{\frac{\sqrt{3}}{2}}\)

\(AC = \frac{2}{\sqrt{3}}\)

Thus, the length of side \(AC\) is \(\frac{2}{\sqrt{3}} \text{ m}\).

Therefore, the correct answer is \(\frac{2}{\sqrt{3}} \text{ m}\).

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Similar Questions

  1. In the given figure, if \(RS = 3\sqrt{3} \text{ cm}\) and \(RPS\) is an equilateral triangle, then find the value of \(QR\)

  2. In a right angled triangle, with angle at \(A\) being \(90^\circ\), the side \(AB\) is of length 3cm and \(BC\) is 12 cm. What is the length of side \(AC\)?
  3. For a pair of similar triangles shown in the figure, the angles made at $B$ and $R$ are same in both the triangles $BAC$ and $RAQ$. If the ratio of the areas of the two triangles is 2:1, and if the area of $BAC$ is $100\text{ cm}^2$ then what is the area of $RAQ$ in sq.cm.?

  4. In a right angled triangle, with angle at A being , the side $AB$ is of length 4cm and $BC$ is 15 cm. What is the length of side $AC$?

     

     

  5. Triangles $PQR$ and $ABC$ are similar triangles.
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Important Questions from Triangles

  1. What is \(AB + BC\) equal to?
     

  2. In the given figure, if \(RS = 3\sqrt{3} \text{ cm}\) and \(RPS\) is an equilateral triangle, then find the value of \(QR\)

  3. In a right angled triangle, with angle at \(A\) being \(90^\circ\), the side \(AB\) is of length 3cm and \(BC\) is 12 cm. What is the length of side \(AC\)?
  4. For a pair of similar triangles shown in the figure, the angles made at $B$ and $R$ are same in both the triangles $BAC$ and $RAQ$. If the ratio of the areas of the two triangles is 2:1, and if the area of $BAC$ is $100\text{ cm}^2$ then what is the area of $RAQ$ in sq.cm.?

  5. In a right angled triangle, with angle at A being , the side $AB$ is of length 4cm and $BC$ is 15 cm. What is the length of side $AC$?

     

     

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