JEE MATHEMATICS MCQ: TRIGONOMETRIC EQUATIONS

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Application +4 | -1

\mathrm{A}+\mathrm{B}+\mathrm{C}=\pi

, then

\cos \mathrm{A}+\cos \mathrm{B}-\cos \mathrm{C}=

View answer and explanation

Correct option: D

-1+4 \cos \frac{\mathrm{A}}{2} \cos \frac{\mathrm{B}}{2} \sin \frac{\mathrm{C}}{2}

Option D (

-1+4 \cos \frac{{\mathrm{{A}}}}{{2}} \cos \frac{{\mathrm{{B}}}}{{2}} \sin \frac{{\mathrm{{C}}}}{{2}}

) is correct because it represents the simplified form of

\cos A + \cos B - \cos C

when

A + B + C = \pi

, using trigonometric identities.

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