एक समद्विबाहु त्रिभुज ABC में यदि AB = AC = 26 सेमी और BC = 20 सेमी है, तो त्रिभुज ABC का क्षेत्रफल ज्ञात कीजिए।

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  1. 180 सेमी2
  2. 240 सेमी2
  3. 220 सेमी2
  4. 260 सेमी2

Answer (Detailed Solution Below)

Option 2 : 240 सेमी2
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दिया है:

एक समद्विबाहु त्रिभुज ABC में,

AB = AC = 26 सेमी और BC = 20 सेमी

गणना:

F1 Ashish Ravi 25.10.21 D1

त्रिभुज ABC में

∆ADC = 90° (समद्विबाहु त्रिभुज में सम्मुख शीर्ष से एक रेखा द्वारा असमान भुजा के मध्य बिंदु पर बनाया गया कोण 90° होता है)

अतः,

AD² + BD² = AB²    (पाइथागोरस प्रमेय से)

⇒ AD² = 576

⇒ AD = 24

त्रिभुज का क्षेत्रफल = ½(आधार × ऊँचाई)

⇒ ½(20 × 24)  (त्रिभुज का क्षेत्रफल = (1/2) आधार × ऊँचाई)

⇒  240 सेमी²

∴ सही विकल्प विकल्प 2 है।

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