Mathematics · 2019
JEE Main · 12 January 2019, Shift 2 · Q88
If sin^4 α+4 cos^4 β+2=4 √ 2 sin α cos β; α, β ∈[0, π], then cos (α+β)- cos (α-β) is equal to:
If $\displaystyle \sin ^4 \alpha+4 \cos ^4 \beta+2=4 \sqrt{2} \sin \alpha \cos \beta$; $\displaystyle \alpha, \beta \in[0, \pi]$, then $\displaystyle \cos (\alpha+\beta)-\cos (\alpha-\beta)$ is equal to :
Official answer
(2)
$\displaystyle -\sqrt{2}$
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JEE Main 2019 Mathematics question, with the answer from NTA’s final answer key. Where our answers come from.