JEE Main 2024 Mathematics question
Not in JEE syllabus
In a triangle ABC, BC = 7, AC = 8, AB = α ∈ N and cosA = . If 49cos(3C) + 42 = , where gcd(m, n) = 1, then m + n is equal to .
Answer: 39
Solution
49 = 64 + α² − (32/3)α gives 3α² − 32α + 45 = 0, so α = 9 (natural). Then cos C = (49 + 64 −
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