Comprehension

आने वाले दो (02) प्रश्नों के लिए निम्नलिखित पर विचार कीजिए: मान लीजिए ABC एक त्रिभुज है, जो B पर समकोणीय है और AB+AC = 3 इकाई है।

त्रिभुज का अधिकतम क्षेत्रफल कितना है?

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NDA-I (Mathematics) Official Paper (Held On: 13 Apr, 2025)
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  1. \(\sqrt{3}/2\)
  2. \(\sqrt{3} \)
  3. \(\sqrt{6}/2\)
  4. \(\sqrt{6}\)

Answer (Detailed Solution Below)

Option 1 : \(\sqrt{3}/2\)
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Detailed Solution

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गणना:

दिया गया,

\(AB + AC = 3\)

मान लीजिए \(AB = x\) और \(AC = 3 - x \)

तब,

\(BC = \sqrt{AC^2 - AB^2} = \sqrt{(3 - x)^2 - x^2} = \sqrt{9 - 6x} \)

त्रिभुज का क्षेत्रफल है,

\(A = \tfrac12\,x\,BC = \tfrac12\,x\,\sqrt{9 - 6x}\)

अधिकतम करने के लिए, \(x\) के संबंध में अवकलन करते हैं और शून्य पर सेट करते हैं:

\(\displaystyle \frac{d}{dx}\bigl(x\sqrt{9-6x}\bigr) = \sqrt{9-6x} \;-\;\frac{6x}{2\sqrt{9-6x}} = 0 \;\Longrightarrow\; x = 1 \)

\(x = 1\) पर, हमें \(BC = \sqrt{9 - 6} = \sqrt{3}\) प्राप्त होता है, अतः

\(A_{\max} = \tfrac12 \times 1 \times \sqrt{3} = \frac{\sqrt{3}}{2}\)

∴ अधिकतम क्षेत्रफल \(\frac{\sqrt{3}}{2}\) वर्ग इकाई है।

अतः, सही उत्तर विकल्प 1 है।

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