The value of cos 25 5 ∘ + sin 19 5 ∘ is

Consider cos 25 5 ∘ + sin 19 5 ∘ = cos ( 27 0 ∘ − 1 5 ∘ ) + sin ( 18 0 ∘ + 1 5 ∘ ) = − sin 1 5 ∘ − sin 1 5 ∘ = − 2 sin 1 5 ∘ = − 2 ( 2 2 3 − 1 ) = − ( 2 3 − 1 )

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Mathematics - Trigonometric Ratios & Identities Question with Solution | TestHub

MathematicsTrigonometric Ratios & IdentitiesBasic Identities & T RatiosMedium2 minPYQ_2012

MathematicsMediumsingle choice

The value of $cos 25 5^{\circ} + sin 19 5^{\circ}$ is

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Solution:

Consider $cos 25 5^{\circ} + sin 19 5^{\circ}$ $= cos (27 0^{\circ} - 1 5^{\circ}) + sin (18 0^{\circ} + 1 5^{\circ}) = - sin 1 5^{\circ} - sin 1 5^{\circ} = - 2 sin 1 5^{\circ} = - 2 (\frac{3 - 1}{2 2}) = - (\frac{3 - 1}{2})$

Stream:JEESubject:MathematicsTopic:Trigonometric Ratios & IdentitiesSubtopic:Basic Identities & T Ratios

⏱ 2mℹ️ Source: PYQ_2012

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