iran-konkur 2022 Q112

iran-konkur · Other · konkur-riazi_1401_specialized Addition & Double Angle Formulae Geometric Configuration with Trigonometric Identities
112. In triangle $ABC$, angle $A$ is $25$ degrees more than angle $B$. What is $2\cos A \sin B - \sin C$?
(1) $\dfrac{\sqrt{2}}{2}$ (2) $-\dfrac{\sqrt{2}}{2}$ (3) $\dfrac{\sqrt{2}}{2}$ (4) $-\dfrac{\sqrt{2}}{2}$
\textbf{112.} In triangle $ABC$, angle $A$ is $25$ degrees more than angle $B$. What is $2\cos A \sin B - \sin C$?

(1) $\dfrac{\sqrt{2}}{2}$ \qquad (2) $-\dfrac{\sqrt{2}}{2}$ \qquad (3) $\dfrac{\sqrt{2}}{2}$ \qquad (4) $-\dfrac{\sqrt{2}}{2}$