Published by:
CGP EDU Academic Team
Published on: August 13, 2026
In any triangle ABC, if 2 Δ a – b 2 c = c 3 , (where Δ is is the area of triangle), then prove that ∠ A is obtuse
Text Solution
Verified by ExpertsThe correct answer is:
2
2 Δ a – b 2 c = c 3
⇒ 2 Δ a 2 b = abc (b 2 + c 2 )
⇒ 
⇒ 
= b 2 + c 2
⇒ a 2 sinB = b 2 + c 2
If sinB = 1, then a 2 = b 2 + c 2 , which is not possible
∴ sinB ≠ 1
∴ cosA = 
= 
< 0
∴ A is obtuse
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