Simplification of Trigonometric Expressions with Specific Angles
Simplify a numerical trigonometric expression involving specific degree/radian values (e.g., sin 70°, cot 10°, sin 48°/sin 16°) to a closed-form value using identities.
106- If $f(\alpha) = 4\sin(\alpha)\cos(2\alpha) + 2\sin(\alpha)$, what is the value of $f\!\left(\dfrac{41\pi}{9}\right)$? (1) $-\sqrt{3}$ (2) $\sqrt{3}$ (3) $1$ (4) $-1$
The value of $2\sin\frac{\pi}{22}\sin\frac{3\pi}{22}\sin\frac{5\pi}{22}\sin\frac{7\pi}{22}\sin\frac{9\pi}{22}$ is equal to: (1) $\frac{1}{16}$ (2) $\frac{5}{16}$ (3) $\frac{7}{16}$ (4) $\frac{3}{16}$
$$\frac{\tan 60^{\circ}}{\sin 20^{\circ}} - \frac{1}{\cos 20^{\circ}}$$ Which of the following is this expression equal to? A) 4 B) 2 C) 1 D) $\frac{\sqrt{3}}{2}$ E) $\frac{1}{2}$
$$\frac{1+\cos 40^{\circ}}{\cos 55^{\circ} \cdot \cos 35^{\circ}}$$ Which of the following is this expression equal to? A) $\cos 20^{\circ}$ B) $2\cos 20^{\circ}$ C) $4\cos 20^{\circ}$ D) $\cos 40^{\circ}$ E) $2\cos 40^{\circ}$