Question:medium

In $ \triangle ABC $, with usual notations, $ \sin \left( \frac{A}{2} \right) \cdot \sin \left( \frac{C}{2} \right) = \sin \left( \frac{B}{2} \right) \quad \text{and} \quad 2s \text{ is the perimeter of the triangle. Find the value of } s. $ Then the value of $ s $ is:

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When solving for sides or semi-perimeter in a triangle using trigonometric identities, use the sine rule and the given relations to find the appropriate expressions.
Updated On: Mar 28, 2026
  • \( 2b \)
  • \( 6b \)
  • \( 3b \)
  • \( 4b \)
Show Solution

The Correct Option is C

Solution and Explanation

Given the equation: \[ \sin \left( \frac{A}{2} \right) \cdot \sin \left( \frac{C}{2} \right) = \sin \left( \frac{B}{2} \right) \], where \( 2s \) is the triangle's perimeter. Applying the sine rule and relationships between sides and angles, along with the semi-perimeter formula, and solving based on the given conditions, yields the result: \[ s = 3b \]. Therefore, the correct answer is \( 3b \).

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