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CGP EDU Academic Team
Published on: August 13, 2026
In Δ ABC (a + b)(a – b) = c(b + c), the measure of angle A, is-
Text Solution
Verified by ExpertsThe correct answer is:
D
Assume that side 'a' is opposite to ∠ A
Given, (a + b)(a – b) = c(b + c)
⇒ a 2 – b 2 = c 2 + bc
a 2 = b 2 + c 2 + bc = b 2 + c 2 – 2bc cosA (By law of cosines)
bc = –2bc cosA
cosA = –1/2 or ∠ A = 120 0
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