Cos198° + Sin432° + tan12° + tan168° এর মান কত?

Cos198° + Sin432° + tan12° + tan168° এর মান নির্ণয়:

আমরা জানি, cos(180° + θ) = -cosθ এবং sin(360° + θ) = sinθ

\( \therefore \) Cos198° = Cos(180° + 18°) = -Cos18°

\( \therefore \) Sin432° = Sin(360° + 72°) = Sin72°

আবার, tan(180° - θ) = -tanθ

\( \therefore \) tan168° = tan(180° - 12°) = -tan12°

সুতরাং, Cos198° + Sin432° + tan12° + tan168° = -Cos18° + Sin72° + tan12° - tan12°

আমরা জানি, Sin(90° - θ) = Cosθ

\( \therefore \) Sin72° = Sin(90° - 18°) = Cos18°

অতএব, -Cos18° + Sin72° + tan12° - tan12° = -Cos18° + Cos18° + tan12° - tan12° = 0 🥳

সুতরাং, Cos198° + Sin432° + tan12° + tan168° = 0 🤩