For the functions f(θ) = αtan^2θ + βcot^2θ, and g(θ) = αsin^2θ + βcos^2θ, α > β > 0, let min_0 < θ < π/2f(θ) = max_0 < θ < πg(θ). If the first term…
JEE Main 2026 — Mathematics Algebra
2026integermedium
For the functions f(θ)=αtan2θ+βcot2θ, and g(θ)=αsin2θ+βcos2θ, α>β>0, let min0<θ<π/2f(θ)=max0<θ<πg(θ). If the first term of a G.P. is (2βα), its common ratio is (α2β) and the sum of its first 10 terms is nm, gcd(m,n)=1, then m+n is equal to _______.
Official previous-year question
Held on 6 Apr 2026 · Verified 6 Jul 2026.
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Solution
For the function f(θ)=αtan2θ+βcot2θ, applying the AM-GM inequality gives:
αtan2θ+βcot2θ≥2αtan2θ⋅βcot2θ=2αβ
Thus, min0<θ<π/2f(θ)=2αβ.
For the function g(θ)=αsin2θ+βcos2θ, we can rewrite it as:
g(θ)=αsin2θ+β(1−sin2θ)=β+(α−β)sin2θ
Since α>β>0, the maximum value of g(θ) occurs when sin2θ is maximum, which is 1 (at θ=π/2).